Hi Alfred,
Once that is working fine, you should be able to find the snag in your project.
I don't this is the cause of your PlatformNotSupportedException, I suggest you migrate from the explicit .dna files in your project to having the ribbon files embedded as resources in your C# project. There are different ways to do this in the project, and load again when you need to. The project shows one that is more verbose on the project file, but simpler in the code. RunTagMacro is supported as before.
-Govert