So I have another noodle-scratcher (for me anyway).
I\'m trying to create my own custom control in a CMS I only have partial source code for (i.e. samples the vendor
Try putting your partial class in
namespace CMS.Web
I was getting this error when the name of the class that was extending the UserControl class was not the name used in ASP inclusion. I made the change to the class name and redeployed the solution. The problem was fixed.