Clamp simulation with contact

Hi folks,
here the little simplified assembly in creo 8.0.9.

I tried to simulate with Simulate the effect over a stator of a clamp.
The program gives to me always the error "Creo Simulate could not generate elements for all of the
entities in the model"
I've just tried to mesh the single parts and it works. The problem is only in the assembly with the part of the stator. I tried also:

• without the symmetry
• with different fixing
• fixing all the dof for better numerical stability
• without contact interface

I don't know where I'm going wrong.