Hello Kazim,
This scenario is not supported. In its core RadHtmlPlaceholder is an IFrame that is being rendered on top of the Silverlight plugin. As far as I managed to test your particular scenario, the internal IFrame throws an access denied error and we cannot do much about it. I believe the quick redirection is a viable option in your scenario.
Greetings,
Kiril Stanoev
the Telerik team
Explore the entire Telerik portfolio by downloading the Ultimate Collection trial package. Get it now >>