Unfortunately the provided information is not sufficient to describe us the cause of the issue or your specific scenario. Can you please elaborate by sharing detailed information about what you want to achieve and send us some sample screenshots?
I suggest you to check out the following example which demonstrates using a User Control to edit a RadGrid:
Hope this helps.
the Telerik team
If you want to get updates on new releases, tips and tricks and sneak peeks at our product labs directly from the developers working on the RadControls for ASP.NET AJAX, subscribe to their blog feed