"Unable to cast object of type TabPages.PJKTabPage to type TabPages.PJKTabPage"

I encountered this error before. You probably reference the same assembly and then you try to load it from a different location. ( Once referenced, .net copies it to some diff path). So even if you have the same types returned, they dont match being from 2 physically different dlls.
Look in the AppDomain to see whether the assembly is loaded, and if not, try to load id via Assembly.Load(FullyQUalifiedName) not LoadFrom.
This should fix the casting adn parameter issue.

I can send u the code on monday if needed.
V