Please, accept our apologies for the delayed response.
We were not able to reproduce the problem you experience with a simple test project. Please, sent us a simple running project which reproduces the issue so that we can test it locally, research the problem and do out best to help you.
You will need to open a support ticket in order to have the right to attach files. Please, download a trial version of the RadControls for ASP.NET AJAX suite and you will have the right to open a support ticket. For your convenience I have attached a screenshot with instructions how to open a support ticket.
We will be glad to help you.
the Telerik team