Durchschuss76

Hello, I downloaded the to realize a spinning upper stage. So I placed two docking parts under my upper stage and set it up. The Problem is the upper dock begins to rotate but what happens is that the upper stage is just sheared of the docking part and falls apart instead of rotating, it seems like the upper stage don't want to rotate as long its attached. I would be pleased if someone could help me with this problem. Greets Durchschuss