I have this code
<asp:LinkButton ID="LinkButton1" runat="server" Text="LinkButton" />
<asp:DragPanelExtender ID="DPE1" runat="server" DragHandleID="pnl1" TargetControlID="Panel1" />
<asp:Panel ID="Panel1" runat="server" Style="display: none; background-color: White;">
<asp:Panel ID="pnl1" runat="server">
<table style="background-color: AppWorkspace;">
<tr>
<td align="center">
<asp:Label ID="lblHeader" runat="server" Text="Header testing" ForeColor="White" />
</td>
<td align="right">
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
<asp:ImageButton ID="CancelButton1" runat="server" CausesValidation="False" Height="20px"
ToolTip="Close" AlternateText="Close" ImageUrl="~/images/close.jpg" OnClick="CancelButton1_Click" />
</ContentTemplate>
</asp:UpdatePanel>
</td>
</tr>
</table>
</asp:Panel>
<asp:Panel ID="pnl2" runat="server">
<asp:UpdatePanel ID="UpdatePanel2" runat="server">
<ContentTemplate>
<p>
Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem
Ipsum has been the industry's standard dummy text ever since the 1500s,
</p>
<asp:Button ID="btn" runat="server" Text="test" OnClick="btn_Click" />
</ContentTemplate>
</asp:UpdatePanel>
</asp:Panel>
</asp:Panel>
<asp:ModalPopupExtender ID="ModalPopupExtender1" runat="server" BackgroundCssClass="modalbackground"
PopupControlID="Panel1" TargetControlID="LinkButton1" PopupDragHandleControlID="DPE1"
CancelControlID="CancelButton1" Drag="true" />
<asp:Label ID="lbl" runat="server" />
I am getting the above exception when I click the CancelButton1 after the test button
Why? and how to resolve this issue?
Thanks in advance for any help
