Can't seem to figure out the problem here. I created a new website in Sitefinity 4.0 BETA 2. I opened the website in Visual Studio 2010. I created a folder called Controls and in that, created a User Control called units.ascx that has a basic RadGrid in it. I added the User Control to my toolbox using the instructions here:
It appears in my toolbox with no problems. I created a page and used one of the standard templates. When I try to drag my control to one of the sections, I get the following error
Could not load type 'SitefinityWebApp.Controls.units'
Did I miss something when I was adding the control to my toolbox or creating the user control in VS?