Update Panel not updating despite of clicking the buttons assigned to triggers

Hello everyone,

I have a gridview , some labels and a dropdown inside an update panel. I have three buttons insert, update and delete. I have created three asyncpostback triggers and assigned them to the buttons and event click. The insert, update, Delete buttons work but the update panel does not update. I have scoured the web for a solution but found cannot figure out what I'm doing wrong. Any help would be greatly appreciated. Here's my code.

<form id="form1" runat="server"><div><div><asp:ScriptManager ID="ScriptManager1" runat="server"></asp:ScriptManager><asp:SqlDataSource ID="caldropsource" runat="server"
            ConnectionString="<%$ ConnectionStrings:ConnectionString %>"
            SelectCommand="SELECT [Event] FROM [Eventcal]"></asp:SqlDataSource><asp:UpdatePanel ID="UpdatePanel1" runat="server"><Triggers><asp:AsyncPostBackTrigger ControlID = "Event_Insert" EventName ="click" /><asp:AsyncPostBackTrigger ControlID ="Event_Update" EventName ="click" /><asp:AsyncPostBackTrigger ControlID ="Event_Delete" EventName ="click" /></Triggers><ContentTemplate ><asp:DropDownList ID="caldropdown" runat="server" DataSourceID="caldropsource"
            DataTextField="Event" DataValueField="Event" AppendDataBoundItems ="true"
            AutoPostBack="True"><asp:ListItem Text = "Select Item"></asp:ListItem></asp:DropDownList><asp:GridView ID="calgrid" runat="server" AutoGenerateColumns="False"
            DataSourceID="calsource"><Columns><asp:BoundField DataField="Event" HeaderText="Event" SortExpression="Event" HeaderStyle-BackColor="#0066FF" HeaderStyle-ForeColor="White" ControlStyle-Font-Bold ="true" /><asp:BoundField DataField="eventdate" HeaderText="Event Date" DataFormatString="{0:d}"
                    SortExpression="eventdate" HeaderStyle-BackColor="#0066FF" HeaderStyle-ForeColor="White" ControlStyle-Font-Bold ="true" /><asp:BoundField DataField="eventtime" HeaderText="Event Time"
                    SortExpression="eventtime" HeaderStyle-BackColor="#0066FF" HeaderStyle-ForeColor="White" ControlStyle-Font-Bold ="true" /></Columns></asp:GridView><asp:SqlDataSource ID="calsource" runat="server"
            ConnectionString="<%$ ConnectionStrings:ConnectionString %>"
            SelectCommand="SELECT * FROM [Eventcal]"></asp:SqlDataSource><asp:Label ID="Label1" runat="server" Text="Add Event/Update Event"></asp:Label><br />
        Selected Event:<br /><asp:Label ID="Eventlabel" runat="server"></asp:Label><asp:Label ID="Eventdatelabel" runat="server"></asp:Label><asp:Label ID="EventTimeLabel" runat="server"></asp:Label></ContentTemplate></asp:UpdatePanel><br /><br /><asp:TextBox ID="Eventbox" runat="server"></asp:TextBox><asp:TextBox ID="Eventdatebox" runat="server"></asp:TextBox><asp:TextBox ID="Eventtimebox" runat="server"></asp:TextBox><br /><asp:Button ID="Event_Insert" runat="server"
            style="z-index: 1; left: 119px; top: 357px; position: absolute" Text="Insert" /><asp:Button ID="Event_Update" runat="server"
            style="z-index: 1; left: 192px; top: 357px; position: absolute" Text="Update" /><br /><asp:Button ID="Event_Delete" runat="server"
            style="z-index: 1; left: 274px; top: 357px; position: absolute" Text="Delete" /><br /><br /><br /><br /><br /><br /></div></div></form>

Thank you in advance,

Sai.