Hello all,

I am trying to model a system where I am punching a viscoelastic thin film with an analytically rigid punch. The error I run into is the following:
 "The rigid bodies with the reference nodes contained in node set ErrNodeRefNodeNoMass have no mass associated with them and some degrees of freedom of the reference node are not restrained. Either mass must be defined or all of the translational degrees of freedom must be constrained. See the status file for further details."

I find this odd because I originally had a mass assigned in the 'assembly' tab to the reference point on the center bottom face of the punch. I then had the idea that maybe I needed to assign a mass to the reference point under the 'part' tab and still the error came up. Ultimately, I can't figure out how to assign mass to the punch yet that is what is holding me back. Am I missing something? 

Thanks,
Sean