Place Nested Child GridView inside UpdatePanel for Asynchronous Expand and Collapse in ASP.Net

Hello,

I have another problem, and I hope someone can give me a clue.

I tryed to put a nested Gridviews (parent-child) in an UpdatePanel, but it didn 't work as I want. Firstly the code of the Gridview (its from the example reffering to this http://aspsnippets.com/Articles/Multilevel-N-Level-Nested-GridView-GridView-inside-GridView-in-ASPNet-with-Paging.aspx)

<form id="form1" runat="server"> 
  <asp:ScriptManager ID="scriptMgr" runat="server"  EnablePartialRendering="true" />
 <asp:UpdatePanel ID="updatePnl" runat="server" UpdateMode="Conditional">
 <ContentTemplate>
    <asp:GridView ID="gvCustomers" runat="server" AutoGenerateColumns="False" CssClass="Grid"
        DataKeyNames="CustomerID" onrowcommand="RowCommand1"> 
        <Columns>             <asp:TemplateField> 
                <ItemTemplate> 
                    <asp:ImageButton ID="imgOrdersShow" runat="server" OnClick="Show_Hide_OrdersGrid" ImageUrl="~/images/plus.png"
                        CommandArgument="Show" /> 
                    <asp:Panel ID="pnlOrders" runat="server" Visible="false" Style="position: relative"> 
                    
                        <asp:GridView ID="gvOrders" runat="server" AutoGenerateColumns="false" 
                            CssClass="ChildGrid"
                            DataKeyNames="OrderId" onrowcommand="RowCommand2"> 
                            <Columns>                                
                                <asp:BoundField ItemStyle-Width="150px" DataField="OrderId" HeaderText="Order Id" /> 
                                <asp:BoundField ItemStyle-Width="150px" DataField="OrderDate" HeaderText="Date" /> 
                                  <asp:ButtonField Text="Schaltfläche" CommandName="ClickLVL2" />
                            </Columns> 
                        </asp:GridView> 
                    </asp:Panel>                 </ItemTemplate> 
            </asp:TemplateField> 
            <asp:BoundField ItemStyle-Width="150px" DataField="ContactName" 
                HeaderText="Contact Name" > 
             <ItemStyle Width="150px"></ItemStyle>
            </asp:BoundField>
            <asp:BoundField ItemStyle-Width="150px" DataField="City" HeaderText="City" > 
            <ItemStyle Width="150px"></ItemStyle>
            </asp:BoundField>
            <asp:ButtonField  Text="Schaltfläche" CommandName="ClickLVL1" />
                    </Columns>     </asp:GridView> 
     <asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>
        </ContentTemplate>      <Triggers>
         <asp:AsyncPostBackTrigger ControlID="gvCustomers" EventName="RowCommand" />
      </Triggers>        </asp:UpdatePanel>          
    </form> </body> 

In the Codebehind I put a "updatePnl.Update()" where I needed it.

I don't want a Postback on RowCommand. With this Trigger, the AsyncPostBack works well for the RowCommand, but the nested GridView won't be added in the new Row. With a PostbackTrigger it works, so I try to execute an PostbackTrigger when I click on the ImageButton.  But then an exception will be thrown. When I put "

EnablePartialRendering="false"

 in the scriptManager, no exception will be shown, but on RowCommand a complete Postback is done.

Any solutions for this problems?