why do I receive an error message when working on simulation

As above, I am making a hexapod robot (each leg has 3 DOF). I would like to do the hexapde gait simulation and analysis, so as to obtain a smooth locomotion and walking steps. But when I tried to run the simulation, I got the following error:

Primitive R3 was not found on the Joint. Select a legal primitive to actuate in the Joint Actuator dialog.