Singularities in the mesh of a rotating machinery model.

I am running a time dependent simulation in the Rotating machinery-laminar flow module.The simulation attemps to show the mixing process of a fluid in a mixer with different geometries.For my first model, I used a cylindrical geometry for the cointainer and the simulation worked. However, when I used a conical geometry the simulation did not converge and the follow warning came up:


The model may have a singularity. New constrain force nodes detected. These are not stored.

Does anybody know how can I solve this problem?

Thanks