thank you for the answers.
You are right, I need Reflection because I read from a XML to dynamically map Buttons to Commands.
But now I solved it a better way.
I have a VM where the View with the Buttons is bound to and where I have a lot of SimpleCommands.
Behind the Buttons is only one SimpleCommand, which is an Orchestrator to dynamically execute via Relfection. In this VM the Reflection is doing fine.
But from another VM, which also has to execute these SimpleCommands, these Commands are connected through the MEF Mechanism.
So, I had a knot in my brain, but no need to separately do the Reflection mechanism in this second VM. I only have to call the "Orchestrator"-Command in the first VM.
Thank you for your efforts and for your great framework!