own subclass deriving from RibbonButton error

Dec 2, 2008 at 4:46 PM
Whem I create my own subclass deriving from RibbonButton i get an errormessage in the Designer, but it works fine when running.
Any idea why ?
The errormessage is something like: A value of type 'MyRibbonButton' cannot be added to a collection or dictionary of type `1