Please note that the RadFormDecorator applies skinning to the HTML elements on the page, rather than the RadControls for ASP.NET AJAX. You can find the full list of skinned elements in this help article
If you want to control the skinning of multiple RadControls you can either use the RadSkinManager
or register the skin globally
in web.config (check the last section) if you want it applied to the whole site.
As for the issue you have encountered, please elaborate so that I can help you accordingly. If the controls are unresponsive, this could mean that there is a problem with their client-side objects, although I cannot suggest anything concrete without examining the actual setup. Please try preparing a simple, fully runnable sample that isolates the issue so that I can inspect it locally and provide a more to the point answer.
Explore the entire set of ASP.NET AJAX controls we offer here
and browse the myriad online demos
to learn more about the components and the features they incorporate.