Weaverbird: ArgumentException: Invalid Path

Hey..

Yesterday I installed Weaverbird on my Grasshopper, following all the rules like just do copy .dll and .gha files in the right folder. I can see the toolbar and i can add them in the working space.

But as soon as I am connecting them to the mesh i have instantly the same error: ArgumentException: Invalid Path. 

I have the latest version of the Rhino WIP for mac and the latest version of the Weaver Bird.

Could someone help me?