It shouldn't be an error if the nodes aren't coincident. The COMBI14 Assumptions and Restrictions has the bullet item:
For noncoincident nodes and KEYOPT(2) = 1, 2, or 3, no moment effects are included. That is, if the nodes are offset from the line of action, moment equilibrium may not be satisfied. Â
You are using somewhat archaic commands, EN and LSSOLVE. What version are you running? RBE3 (force distribution constraint equations) is an unusual way to connect nodes. CERIG would be a fixed connection.
You are navigating away from the AIS Discovery experience