Based on the information supplied, it is hard to pinpoint the cause of the issue which you described. To properly address it, it will be best if you open a formal support ticket, and send us a small working project, demonstrating your setup, and showing the unwanted behavior. We will review it locally, and advise you further.
All the best,
the Telerik team
Let us know about your Windows Phone 7 application built with RadControls and we will help you promote it. Learn more>>