Error: Adding Static Body

Hello Jose, first of all congratulations and big thanks for this nice workbench. I've seen your example videos. Very cool.

I have followed your installation instructions and I can get the workbench to work. I can also load examples and run them.

But while creating own examples I always get the following problems. Please look at the video, I've made: https://www.youtube.com/watch?v=J4raIgQxd2E

The Body cannot be added and errors are thrown. A "dummy body" is added at the lower end of the "object browser"(FreeCAD Tree on the left) and under the mbdyn elements bodies no static body is appearing.

My System is Windows 10 and I've tried both FC 0.20.1 and FC 0.20.0 with your workbench.

Thank's in advance for dealing with my problems.

Kind Regards Simon