Extender Controls not compiling

Hello ,

I recently started working with Ajax/Atlas. I have set up atlas extensions , and am trying to add the control toolkit . I follwoed the instructions , The items show up in the toolbox. When I drag any of the controls onto a webform . Intellisense tell me that the control is not a known element.

I realize this is vague, but if anyone can point me in the right. direction .

Thanks in advance

It seems to be related to how the controls are registered in the site . I have opened other sample projects where the controls are being used and they work fin, in that project .