button in update panel only fires on second click?

hi,

I have an update panel with a link button and image button. both are bound to events

only the link button works first click the Image button in bold below only works on Second click?


          
         <asp:UpdatePanel ID="UpdatePanel7" runat="server">



            <ContentTemplate>




        
    <asp:Panel ID="Panel8" runat="server" Visible="False">
    
   <h2>CONFIRMATION FORM</h2>


    

<asp:TextBox ID="txtDate1" runat="server"/> <asp:ImageButton ID="Calender" runat="server" ImageUrl="Calender.png" />

 <cc1:CalendarExtender ID="DateTextBox" TargetControlID="txtDate1" PopupButtonID="Calender" runat="server" />
    

 
        <asp:TextBox ID="Address" runat="server" TextMode="MultiLine" Rows="5" Width="300"></asp:TextBox>

  

                <asp:DropDownList ID="DropDownList1" runat="server" DataSourceID="ObjectDataSource2" DataTextField="CommonName" AppendDataBoundItems="True"
                                                    DataValueField="CountryId">
                 <asp:ListItem Text="--Select Country--" Value="" />   </asp:DropDownList>





                <asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server"
                ControlToValidate="Country" ErrorMessage="SelectCountry" ToolTip="name is required."
                                          SetFocusOnError="True" >*</asp:RequiredFieldValidator>


    <p>
    
       About the peformance:
    </p>
 
        <asp:TextBox ID="Comments" runat="server" TextMode="MultiLine" Rows="5" Width="300"></asp:TextBox>

        
          

<p>If you have agreed a different amount <asp:LinkButton ID="Amount"
        runat="server" onclick="Amount_Click" CausesValidation="False">click here</asp:LinkButton>

        
        </p>

    <asp:Panel ID="Panel9" runat="server" Visible="False">
 


   <p>Select the amount</p>

       <asp:DropDownList ID="DropDownList3" runat="server">
            <asp:ListItem Text="--Select--" Value="" />
              <asp:ListItem Value="150.00" Selected="True">150.00</asp:ListItem>
         <asp:ListItem Value="200.00">200.00</asp:ListItem>
      
  


    </asp:DropDownList>

</p>

        </asp:Panel>



     

        
    <p style="padding-top: 10px; padding-bottom: 10px">

        <asp:ImageButton ID="ImageButton1" onclick="Button52_Click" runat="server" CausesValidation="False" ImageUrl="Images/CheckOutImage.png" />
       
 
    </p>

   

        
    
   </asp:Panel>

        
     
        </ContentTemplate>

 

            <Triggers>
        <asp:AsyncPostBackTrigger ControlID="LinkButton40" EventName="Click" />
    </Triggers>


        </asp:UpdatePanel>