Yes, I've tried that. After a Clean and Rebuild I get the same errors. I restarted VS after the Rebuild and instead of "Invalid Markup" I get a XamlParseException:
A value of type 'GridViewTableDefinition' cannot be added to a collection or dictionary of type 'TableDefinitionCollection'.
This is the code:
I Clean and Rebuild the solution again and the original errors come back (mentioned in my first post). Actually now I'm getting the following error as well.
The local property "AnimationName" can only be applied to types that are derived from "RadAnimation".
That error is being thrown by a TreeViewExpandCollapseAnimation control. I see in the online documentation that this control is in fact derived from RadAnimation. It seems like the compiler isn't finding the inherited classes of these controls for some reason.