FileUpload Control is Returning file Name Null

Hi when i click the btnPostCommentsShare_Click the Fileupload doesn't returning the FileName.

<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>

<asp:DataGrid
Style="margin-bottom: 10px;
border-style: none"
ID="pnlDC_dgrdRevenue"
OnItemDataBound="pnlDC_dgrdRevenue_ItemDataBound"
OnItemCreated="pnlDC_dgrdContact_OnItemCreatedEventHandler"
OnItemCommand="pnlDC_dgrdRevenue_ItemCommand"
OnPageIndexChanged = "pnlDC_dgrd_PageIndexChanged"
AllowPaging="true" PageSize="20"
PagerStyle-NextPageText="N" PagerStyle-PrevPageText="P"
CellPadding="0" AllowSorting="false"
AutoGenerateColumns="False"
ShowHeader="false"
ShowFooter="false"
DataKeyField="p_id"
Visible="true"
Width="100%"
runat="server"
CausesValidation="false"

GridLines="None" BackColor="White" BorderStyle="None" BorderWidth="0px" >
<PagerStyle CssClass="BodyLink2" HorizontalAlign="Right" Mode="NumericPages"></PagerStyle>
<Columns>
<asp:TemplateColumn ItemStyle-BorderStyle="None">
<ItemTemplate>
<asp:PlaceHolder ID="MainPH" runat="server" Visible="true" >
<table border="0" width="100%" cellpadding="0" cellspacing="0" >
<tr style="width:50%;">
<td colspan="2" valign="top">

<ul>
<li>
<asp:TemplateColumn ItemStyle-BorderStyle="None">
<ItemTemplate>
<asp:ImageButton ID="ImageButton1" runat="server" ImageUrl="images/plus.gif"
CommandName="Expand" Visible="false"></asp:ImageButton>
</ItemTemplate>

</asp:TemplateColumn>
<div class="comment-pic">
<asp:TemplateColumn HeaderText="" ItemStyle-BorderStyle="None" ItemStyle-VerticalAlign="Top">
<ItemTemplate>
<asp:Image ID="Image1" valign="top" style="padding-left:05px;" Width="60px" Height="60px" runat="server" ImageUrl='<%# "Cropped_Images/" + Eval("up_user_name")+ ".jpg"%>' />
</ItemTemplate>

</asp:TemplateColumn>
</div>

<div class="comment-text">
<asp:TemplateColumn HeaderText="" ItemStyle-BorderStyle="None" ItemStyle-VerticalAlign="Top">
<ItemTemplate>
<asp:LinkButton ID="pnl_name" align="left" runat="server" CausesValidation="false"
CommandArgument='<%# Eval("name") %>'
OnCommand="pnl_open_ambition" Text='<%# Eval("name") %>' />
<asp:Label ID="pnldrg_lbpost" style="padding-left:10px" align="left" veartical-align="top" Text='<%# Convert.ToString(DataBinder.Eval(Container.DataItem, "p_desc")) %>'
runat="server" CausesValidation="false" />
</ItemTemplate>
</asp:TemplateColumn>
</div>

<p style="float:right;" class="date-time">
<asp:TemplateColumn HeaderText="" ItemStyle-BorderStyle="None" ItemStyle-VerticalAlign="Top" >
<ItemTemplate>
<asp:PlaceHolder ID="PHCommentLike" runat="server" Visible="true">

<asp:Label ID="pnldrg_lbpostdate" runat="server" CausesValidation="false"
Text='<%# Convert.ToString(DataBinder.Eval(Container.DataItem, "postdate")) %>'
/>

<asp:ImageButton ID="lbtnComments" runat="server" CommandName="Comments" width="13" height="13" CausesValidation="false" ImageUrl="images/chat-icon.jpg" ></asp:ImageButton>

<asp:LinkButton ID="pnl_lbLike" align="left" class="comment" runat="server" CausesValidation="false"
CommandArgument='<%# Convert.ToString(DataBinder.Eval(Container.DataItem, "p_id")) %>'
OnCommand="pnl_lbLike_Command" Text='<%#checkTextView(Convert.ToString(DataBinder.Eval(Container.DataItem, "p_id")))%>' />
<asp:Image ID="ImgLike" runat="server" ImageUrl="images/like.gif" ToolTip='<%# Convert.ToString(DataBinder.Eval(Container.DataItem,"username2")) %>' Visible='<%# checkThumbVisible(Convert.ToString(DataBinder.Eval(Container.DataItem, "likes")))%>' />
<asp:Label ID="pnldrg_lbpostLikes" Text='<%# Convert.ToString(DataBinder.Eval(Container.DataItem, "likes")) %>'
cssclass="" runat="server"></asp:Label>


</asp:PlaceHolder>
</ItemTemplate>
</asp:TemplateColumn>
</p>

<p class="delete">
<asp:TemplateColumn HeaderText="" ItemStyle-BorderStyle="None">
<itemtemplate>
<asp:ImageButton ID="ImBtnDeletePost" Tooltip="Remove Journal" CausesValidation="false" Visible='<%# CheckVisible(Convert.ToString(DataBinder.Eval(Container.DataItem, "p_up_id")))%>' runat="server" ImageUrl="images/remove.gif" OnCommand="btnDeletePost_Click" CommandArgument='<%# Convert.ToString(DataBinder.Eval(Container.DataItem, "p_id")) %>' />
</itemtemplate>
</asp:TemplateColumn>
</p>


</li>
</ul>

<asp:TemplateColumn HeaderText="" ItemStyle-BorderStyle="None"
Visible="true">
<ItemTemplate>
<asp:PlaceHolder ID="phpostComments" runat="server" Visible="false">

<tr>
<td colspan="2">
<table border="0" >
<tr style="height:10px"></tr>
<tr>
<td width="16%">
</td>
<td valign="top">
<asp:TextBox ID="txtpostComments" Style="padding-right:10px" TextMode="MultiLine" Columns="38" Rows="2" runat="server" ></asp:TextBox>
</td>

<td valign="middle">
<asp:RequiredFieldValidator ID="rfvUserName1" EnableClientScript="true" ControlToValidate="txtpostComments" ErrorMessage="Please enter Post." runat="server"></asp:RequiredFieldValidator>

</td>

</tr>
<tr>
<td width="16%">
</td>
<td>
<asp:FileUpload ID="uploadImg1" runat="server" />
<asp:FileUpload ID="uploadImg2" runat="server" />

</td>
</tr>
<tr>
<td width="16%">
<td align="right">
<asp:Button ID="btnpostCommentsShare" CssClass="sharebutton" Text="Share" runat="server" CommandArgument='<%# Convert.ToString(DataBinder.Eval(Container.DataItem, "p_id")) %>'
OnCommand="btnPostCommentsShare_Click" />

</td>
</tr>
</table>
</td>
</tr>
<tr style="height:15px"></tr>
</asp:PlaceHolder>
</ItemTemplate>

</asp:TemplateColumn>

</td>

</tr>
<tr>

<td valign="top" align="left" style="padding-left:80px;">
<asp:TemplateColumn ItemStyle-Width="50%" ItemStyle-BorderStyle="None">
<ItemTemplate>
<asp:PlaceHolder ID="Expanded" runat="server" Visible="False" >

<asp:DataGrid Style="margin-bottom: 10px; border-color: White;background-color:#F0F8FF" ID="pnlDC_dgrdRevenueOthers"
OnItemDataBound="pnlDC_dgrdRevenueOthers_ItemDataBound" CellPadding="0" AllowSorting="false"
AutoGenerateColumns="False" ShowHeader="false" ShowFooter="false" DataKeyField="c_p_id"
Visible="true" Width="35%" runat="server" CausesValidation="false" OnItemCommand="pnlDC_dgrdComments_ItemCommand"
GridLines="None">
<Columns>
<asp:TemplateColumn ItemStyle-Width="10%" HeaderText="" ItemStyle-BorderStyle="None" ItemStyle-VerticalAlign="Top"
ItemStyle-Height="40px">
<ItemTemplate>
<asp:Image ID="pnldg2_Image" style="padding:5px; border-bottom:solid 1px #ffffff;" Width="50px" Height="50px"
runat="server" ImageUrl='<%# "Cropped_Images/" + Eval("user_name") %>' />
</ItemTemplate>
</asp:TemplateColumn>
<asp:TemplateColumn ItemStyle-BorderStyle="None" HeaderText=""
ItemStyle-HorizontalAlign="left" ItemStyle-VerticalAlign="Middle">
<ItemTemplate>
<asp:Label ID="pnldrg_lbcomments" Width="450px" height="58px"
Text='<%# Convert.ToString(DataBinder.Eval(Container.DataItem, "c_desc")) %>'
runat="server" CausesValidation="false" />
<asp:Label ID="Label1" Width="100%" style="border-bottom:solid 1px #ffffff;color:#888888" Text='<%# Convert.ToString(DataBinder.Eval(Container.DataItem, "commentdate")) %>'
runat="server" CausesValidation="false" />
</ItemTemplate>

</asp:TemplateColumn>
<asp:TemplateColumn HeaderText="" ItemStyle-BorderStyle="None">
<itemtemplate>
<asp:ImageButton ID="ImBtnDeletePostComment" Style="padding-left:19px" CausesValidation="false"
Visible='<%# CheckVisible(Convert.ToString(DataBinder.Eval(Container.DataItem, "c_up_id")))%>'
Tooltip="Remove Comment" runat="server" ImageUrl="images/remove.gif"
OnCommand="btnDeletePostComment_Click"
CommandArgument='<%# Convert.ToString(DataBinder.Eval(Container.DataItem, "c_id")) %>' />
</itemtemplate>
</asp:TemplateColumn>


</Columns>
</asp:DataGrid>


</asp:PlaceHolder>
</ItemTemplate>

</asp:TemplateColumn>
</td>
</tr>

<tr>
<td align="left" valign="top" colspan="2">
<p class="line2"></p>
</td>
</tr>
</table>
</asp:PlaceHolder>
</ItemTemplate>
<ItemStyle BorderStyle="None" />
</asp:TemplateColumn>
</Columns>
</asp:DataGrid>

</ContentTemplate>

</asp:UpdatePanel>

protected void pnlDC_dgrdRevenue_ItemDataBound(object sender, DataGridItemEventArgs e)
{
DataGrid dgTemp = new DataGrid();
//ImageButton img;
//PlaceHolder exp;
if ((e.Item.ItemType == ListItemType.Item | e.Item.ItemType == ListItemType.AlternatingItem))
{
dgTemp = (DataGrid)e.Item.FindControl("pnlDC_dgrdRevenueOthers");
//Response.Write("UniqueIDvar " + hdfContactUniqueId + " unic" + dgTemp.UniqueID);
if (dgTemp.UniqueID == (hdfContactUniqueId).ToString())
{
dgTemp.EditItemIndex = dgEditItemIndex;

//If the Edit Item Index is -1, On Cancel click
if ((dgEditItemIndex == -1))
{
dgTemp.ShowFooter = true;
}
else
{
dgTemp.ShowFooter = false;
}

//Set the Page Index for child datagrid
dgTemp.CurrentPageIndex = Convert.ToInt32(hdfContactPageIndex.ToString());
////Call the procedure to alter the Current Sort Expression
Session["PrevItemIndex"] = e.Item.ItemIndex;
////Following code is for displaying back child grid after handling its button events
ImageButton img;
img = (ImageButton)e.Item.Cells[0].FindControl("ImageButton1");
img.ImageUrl = "../images/minus.gif";
PlaceHolder exp;
exp = (PlaceHolder)e.Item.Cells[2].FindControl("Expanded");
exp.Visible = true;

dgTemp.DataBind();
//dgUniqueID = "";
dgEditItemIndex = -1;
}
}
try
{
if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
{
DataRowView drvTemp = (DataRowView)e.Item.DataItem;
DataView dvTemp = drvTemp.CreateChildView("ClientRelation");
ImageButton img = null;
PlaceHolder exp = null;
PlaceHolder expH = null;
//Check for record count in child space
if (dvTemp.Count > 0)
{
//Create DataSource for Child DataGrid
((DataGrid)e.Item.FindControl("pnlDC_dgrdRevenueOthers")).DataSource = dvTemp;
}
//If there are no records to display in child space, hide the + sign
else
{
//ImageButton img = null;
//PlaceHolder exp = null;

img = (ImageButton)e.Item.Cells[0].FindControl("ImageButton1");
img.Visible = false;

exp = (PlaceHolder)e.Item.Cells[1].FindControl("Expanded");
exp.Visible = false;
}

((DataGrid)e.Item.FindControl("pnlDC_dgrdRevenueOthers")).DataBind();
//((DataGrid)e.Item.FindControl("pnlDC_dgrdRevenueOthers")).Visible = true;
dgEditItemIndex = e.Item.ItemIndex;

img = (ImageButton)e.Item.Cells[0].FindControl("ImageButton1");
if (img.ImageUrl == "../images/plus.gif")
{
img.ImageUrl = "../images/minus.gif";
}
else
{
img.ImageUrl = "../images/plus.gif";
}
exp = (PlaceHolder)e.Item.Cells[0].FindControl("Expanded");
expH = (PlaceHolder)e.Item.Cells[0].FindControl("PHCommentLike");
expH.Visible = true;
//Response.Write("Expaned" + exp.Visible.ToString());
exp.Visible = !exp.Visible;
Session["PrevItemIndex"] = e.Item.ItemIndex;
Session["ItemValue"] = e.Item.ItemIndex.ToString();
}
}
catch (Exception ex)
{
}
}

protected void pnlDC_dgrdRevenue_ItemCommand(object source, System.Web.UI.WebControls.DataGridCommandEventArgs e)
{
switch (e.CommandName)
{
case "Comments":
////Case for expanding the + sign on Parent grid to show the child grid
TextBox Comments;
Button btnShare;
////(((CheckBox)objItem.Cells[0].FindControl("cbSelected")).Visible=true;
DataGrid dg = (DataGrid)source;
////dg.Columns[5].Visible = true;
////PlaceHolder exp = (PlaceHolder)e.Item.Cells[5].FindControl("phpostComments");
////exp.Visible = Visible = true;
////DataGrid dg1 = (DataGrid)e.Item.FindControl("pnlDC_dgrdRevenue");
////dg1.Columns[5].Visible = true;
////e.Item.Cells[5].Visible = true;
DataGrid dg2 = (DataGrid)e.Item.FindControl("pnlDC_dgrdRevenueOthers");
PlaceHolder expc = (PlaceHolder)e.Item.Cells[0].FindControl("phpostComments");

//PlaceHolder expc = (PlaceHolder)dg.Columns.FindControl("phpostComments");
expc.Visible = !expc.Visible;
//PlaceHolder exp = (PlaceHolder)e.Item.Cells[5].FindControl("phpostComments");
//if (expc.Visible == false)
// exp.Visible = true;
////Session["PrevItemIndex"] = e.Item.ItemIndex;
//Session["ItemValue"] = e.Item.ItemIndex.ToString();
//TextBox comments = (TextBox)dg2.FindControl("txtComments");
//dg2.Visible = true;
//dg2.Columns[2].Visible=true;
//e.Item.Cells[5].Visible=true;
//dg2.Columns[3].Visible = true;

//exp.Visible = !exp.Visible;
//dg2.Visible = true;
// if (comments!=null)
//comments.Visible = true;
//dg2.Columns[3].Visible = true;

//((TextBox)e.Item.Cells[5].FindControl("txtComments")).Visible = true;
//((Button)e.Item.Cells[6].FindControl("btnCommentsShare")).Visible = true;
//if (img.ImageUrl == "../images/plus.gif")
//{
// img.ImageUrl = "../images/minus.gif";
//}
//else
//{
// img.ImageUrl = "../images/plus.gif";
//}

//Session["PrevItemIndex"] = e.Item.ItemIndex;
//Session["ItemValue"] = e.Item.ItemIndex.ToString();
//Store the ItemIndex in session variable
break;

}
}

Please help me,

Thanks,