VBA- AssembleComponent works but not AssembleByCopy

The AssembleComponent command works, but if I substitute the AssembleByCopy command it no longer works and returns a pfcExceptions:XToolkitBadInputs error.  I'm only switching the two lines below:

Set asmcomp = assembly.AssembleComponent(rotormodel, Nothing)

If I replace the line above with the one below, it no longer works

Set asmcomp = assembly.AssembleByCopy("rtr2.prt", rotormodel, False)