Hi Ryan,
I discoverd something verry wierd...
Opening the project properties registration tab shows me a whole diffrent registration as there is in the web.config. So i changed through this interface, now it looks in the web.config like this...
<Controls>
<Control Type="Company.WebGuiControls.TimedTextBox, Company.WebGuiControls, Version=1.0.3531.25185, Culture=neutral, PublicKeyToken=null" />
</Controls>
I also checked the DLL with reflector, the xslt and js files are there so everything looks ok.
But it still doesn't work.