I'm running a static analysis of a truss frame (created with beam weldments) with a large mass at the end.  The large mass is modeled as a solid body.  The only load I'm looking at is gravity, and I have the truss constrained on one end at specified joints.  I'm getting this error (Check that you have applied adequate fixtures to stabilize the mode) after I mesh the model and try to run the solver.

I believe there may be something wrong with how I'm creating the contact between the beam components and the solid body (but I don't know how to check this).  Is there a specific method to create contacts between solid bodies and beams??  I've applied "bonded" contacts with the beams to the face of the solid body.

Any ideas??