I know, how to export and how to import.
I lastly solved the problem today very early in the morning, but can't report earlier, cause of appointments today.
As you try to build a traditional application, which consists of some assemblies, VS2008 automatically generates a build plan based on the dependencies of the projects within a solution. This works
But, when you do MEF, the parts were loosly coupled, there were no dependencies between some projects within a solution, because this is now the job of MEF.
Which of this projects were build first is now of random order, if you were lucky, it works if not you run into the same situation than I.
I do nothing other than 'inject' some dependencies to correct the build plan. I open the 'Project/Project Dependencies' dialog and manually correct the plan.
What a magic, suddenly my sample works, no other changes needed.
Thanks for helping, because I was forced to think more than twice about each detail.
With best regards
So if you wish to import this via the interface IPartA then you will need to export it as Export(GetType(IPartA)) the same goes for IPartB if you want to export it under both interfaces then you will need to put both exports on it.