CustomAttributeNames breaks Updates

[Tayonee]

Whenever i use CustomAttributeNames I am unable to update.  I receive this message:

Sys.WebForms.PageRequestManagerServerErrorException: Error serializing value 'Telerik.Web.UI.Appointment' of type 'Telerik.Web.UI.Appointment.'

If i remove the custom attribute names everything works fine.  Here is a simple test i put together that causes the same issue. My real project actually uses the custom attributes to personalize each event with an image and backgroundcolor.

Any help would be greatly appreciated.

        <telerik:RadScriptManager ID="RadScriptManager1" runat="server" />
        <telerik:RadAjaxPanel ID="RadAjaxPanel1" runat="server" Height="200px" Width="300px">
            <telerik:RadScheduler ID="RadScheduler1" runat="server"
            DataEndField="enddatetime" DataKeyField="ID"  DataSourceID="SqlDataSource1"
            DataStartField="startdatetime" DataSubjectField="subject" Height="593px" Width="1220px"
            WeekView-HeaderDateFormat="MMMM dd" WeekColumnHeaderDateFormat="ddd, dd"
            SelectedDate="2008-07-03" DayEndTime="19:00:00" CustomAttributeNames="ID"
            style="float:left" ShowAllDayRow="False"
            SelectedView="WeekView" StartInsertingInAdvancedForm="True"
            FirstDayOfWeek="Monday" LastDayOfWeek="Friday" WeekHeaderDateFormat="MMMM dd">
            </telerik:RadScheduler>
        </telerik:RadAjaxPanel>
        <asp:SqlDataSource ID="SqlDataSource1" runat="server"
            ConnectionString="<%$ ConnectionStrings:TesterSite %>"
            DeleteCommand="DELETE FROM [tblSimple] WHERE [ID] = @ID"
            InsertCommand="INSERT INTO [tblSimple] ([startdatetime], [enddatetime], [subject]) VALUES (@startdatetime, @enddatetime, @subject)"
            SelectCommand="SELECT * FROM [tblSimple]"
            UpdateCommand="UPDATE [tblSimple] SET [startdatetime] = @startdatetime, [enddatetime] = @enddatetime, [subject] = @subject WHERE [ID] = @ID">
            <DeleteParameters>
                <asp:Parameter Name="ID" Type="Int32" />
            </DeleteParameters>
            <UpdateParameters>
                <asp:Parameter Name="startdatetime" Type="DateTime" />
                <asp:Parameter Name="enddatetime" Type="DateTime" />
                <asp:Parameter Name="subject" Type="String" />
                <asp:Parameter Name="ID" Type="Int32" />
            </UpdateParameters>
            <InsertParameters>
                <asp:Parameter Name="startdatetime" Type="DateTime" />
                <asp:Parameter Name="enddatetime" Type="DateTime" />
                <asp:Parameter Name="subject" Type="String" />
            </InsertParameters>
        </asp:SqlDataSource>

[Tayonee]

Upon further testing with my other project I found the problem is caused by the ID field.  Changed the datasource to pull ID as IDTest and added IDTest to the customattributenames and everything works.