Can you please open a new support ticket and send us a sample running project where the problem can be observed? Also more detailed information about your specific scenario will be helpful.
A little note: When placing RadControls in the XmlHttpPanel please set the panel's EnableClientScriptEvaluation
property to true so that the client-scripts loaded by the RadControl placed inside, are evaluated after a partial update by the XmlHttpPanel.
I am looking forward to receiving your project.
the Telerik team