Ansoft designer and hfss cosimulation

Hi, can anyone let me know that which solution type (HFSS eigen, HFSS driven mode ) should be used for HFSS and Ansoft designer cosimulation. Another problem is i am trying to import a HFSS model in the ansoft designer but the variables used in HFSS model are not being allowed to be tuned or optimized in ansoft designer. I am a bit confused. Can anyone help me out ? Thanks in advance