I examined your code and it seems to be correct. Since I do not have your full source code I am not able to find the problem. However, this online demo is very similar to your scenario and I suggest to examine its full source code and ompare it to yours.
When you install RadControls, our online examples projects are automatically installed on your computer and you can not only examine their full source code, but also extend them further in order to meet your requirements.
You can open the demos from here:
Start\Programs\Telerik\RadControls for ASPNET AJAX\Open Sample WebSite In VisualStudio
The actual location on your hard disk is the following one:
C:\Program Files\Telerik\RadControls for ASPNET AJAX \Live Demos
If this does not help, please prepare a sample, fully runnable demo (including DB, if needed, e.g Northwind), open a new support ticket and send it to me along with detailed reproduction instructions.
the Telerik team
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