problem with the fileexplorer and the scriptmanager

[Konstantin Spielmann]

Hello,

i have a master page and  a page with a radwindowmanager
includes the fileexplorer. 
The master page includes a script manager.
When accessing the page i receive the following error:
"The registration of UpdatePanel with ID "ajax panel" can not be 
canceled because it was not registered with the ScriptManager. 
This can happen if the UpdatePanel was removed from the control 
tree and later added again. This operation is not supported.
Parameter name: updatepanel"

Here is my html code: 

<%@ Page Title="" Language="C#" MasterPageFile="~/MasterPage.master" AutoEventWireup="true" CodeFile="Test.aspx.cs" Inherits="Test" %>

<asp:Content ID="Content1" ContentPlaceHolderID="Main" Runat="Server">
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" Runat="Server">
    <telerik:RadWindowManager ID="RadWindowManager1" runat="server">
        <Windows>
            <telerik:RadWindow ID="RadWindow1" runat="server" style="display:none;">
                <ContentTemplate>
                    <telerik:RadFileExplorer ID="RadFileExplorer1" Runat="server" Language="de-DE" Skin="Windows7">
    </telerik:RadFileExplorer>
                    </ContentTemplate>
            </telerik:RadWindow>
        </Windows>
    </telerik:RadWindowManager>
        <telerik:RadAjaxManager ID="RadAjaxManager1" runat="server">
        <AjaxSettings>
            <telerik:AjaxSetting AjaxControlID="RadWindowManager1">
                <UpdatedControls>
                    <telerik:AjaxUpdatedControl ControlID="RadWindowManager1" UpdatePanelCssClass="" />
                </UpdatedControls>
            </telerik:AjaxSetting>
        </AjaxSettings>
    </telerik:RadAjaxManager>
    </asp:Content>

 Where is my mistake?

Thanks

[Konstantin Spielmann]

here is the solution
http://www.telerik.com/support/kb/aspnet-ajax/window/cannot-unregister-updatepanel-with-id-updatepanelid-since-it-was-not-registered-with-the-scriptmanager.aspx