Normal 0 false false false EN-US X-NONE X-NONE

I created an updatepanel  inside the webexplorerbar and added a button in it.
 the onClick event of button was not not fired at all, please see code below:

    <form id="form1" runat="server">
    <div>
        <asp:ScriptManager ID="ScriptManager1" runat="server">
        </asp:ScriptManager>
        <ig:WebExplorerBar ID="WebExplorerBar1" runat="server" GroupContentsHeight="" Width="250px">
            <Groups>
                <ig:ExplorerBarGroup GroupContentsHeight="" Text="Group">
                    <Items>
                        <ig:ExplorerBarItem TemplateId="Template1" Text="Item">
                        </ig:ExplorerBarItem>
                    </Items>
                </ig:ExplorerBarGroup>
            </Groups>
            <Templates>
                <ig:ItemTemplate ID="WebExplorerBar1Template1" runat="server" TemplateID="Template1">
                    <template>
                        <asp:UpdatePanel ID="UpdatePanel1" runat="server">
                            <ContentTemplate>
                                <asp:Button ID="Button1" runat="server" Text="Button" onclick="Button1_Click" />
                            </ContentTemplate>
                        </asp:UpdatePanel>
                    </template>
                </ig:ItemTemplate>
            </Templates>
            <AutoPostBackFlags ItemClick="On" />
        </ig:WebExplorerBar>
    </div>
    </form>

Any help will be appreciated