Hi,
Thanks for your answer, but infortunaly it doesn't work.
I have tried with CascadingDropDownExtender outside the TabContainer, but Reference null is catched again.
With CascadingDropDownExtender in same Panel as child DropDownList, I have a javascript alert that say Parent Control not found.
Here the code with CascadingDropDownExtender in same Panel as child DropDownList
<cc2:TabPanel runat="server" HeaderText="Carte Identité" ID="TabCI">
<ContentTemplate>
<ProspectMgt:MarketSegmentDropDownList ID="MarketSegmentDropDownList1" runat="server"
AutoPostBack="false" Width="400px"></ProspectMgt:MarketSegmentDropDownList>
<asp:CompareValidator ID="CompareValidator2" runat="server" CssClass="error" ToolTip="Required"
ControlToValidate="MarketSegmentDropDownList1" ValueToCompare="-1" Operator="NotEqual"
ErrorMessage="MktSegment" Display="Dynamic" Font-Bold="True"></asp:CompareValidator>
</ContentTemplate>
</cc2:TabPanel>
<cc2:TabPanel ID="TabSize" runat="server" HeaderText="Size & Volume">
<ContentTemplate>
<asp:DropDownList ID="DropDownListSize" AutoPostBack="false" runat="server">
</asp:DropDownList>
<cc2:CascadingDropDown ID="cddSize" runat="server" TargetControlID="DropDownListSize"
Category="Size" LoadingText="[...]"
ServicePath="~/Modules/ProspectMgt/WebService/ServiceAjax.asmx" ServiceMethod="GetSizeByMktId"
ParentControlID="MarketSegmentDropDownList1" />
</ContentTemplate>
</cc2:TabPanel>
So I don't see why it is not working. It was working perfectly without TabContainer. I'm using AjaxToolKit 30512. However, I'm looking to drop CascadingDropDownExtender and manage this issue by javascript only.