RadControlScenario should add new RadWindow as UserControl, and you should create new instance of it in your code and use its Show() method as shown in this help article
. As far as I can see there is a Microsoft Window instead of RadWindow in the code you send us. So you could try to replace Window with RadWindow and also check if the correct Telerik binaries are added to the references of the project(although they should be added by default when use Telerik scenario).
If you are still having this problem, could you please send us a sample project in order to investigate it further.
the Telerik team