Telerik Controls - Unable to add to form

I am doing Web Forms C# application. I have telerik controls install开发者_Python百科ed. I can see them in toolbox now. But When I drag a control to page, it doesn't do anything. I don't get error too. What could be wrong?

Do you have the register directive added to the page when you drag and drop the control on the VS design surface? You may also try the telerik VS ToolBox configurator to make sure everything is in order: http://www.telerik.com/help/aspnet-ajax/introduction-vsx-toolbox-configuration.html

You just follow the link: http://www.telerik.com/help/aspnet-ajax/introduction-adding-to-app-with-vs.html