The designer inspected the following classes in the file:
Visual Studio was able to identify all the classes in the file; following this error will be a list detailing why each class failed Visual Studio requirements.
The list may include one of the following specific errors:
To correct this error
Derive from a base class that supports designers.
If the class is deriving from something within the project, like an inherited form or control, make sure the project is built by selecting Build Solution from the Build menu.