Driven modal in hfss

I have designed a helix antenna. I used antenna design tool kit in HFSS to create the model. to analyze the model I changed the solution type to driven modal but a message appeared:
terminal 'coax_pin_T1': terminals are not used when the solution type is driven modal.
Is my analysis in this situation correct? in fact i want to determine s11 and mutual coupling(s12)
thanks