Can't get accurate results with Ansoft Designer 2.2

I have been trying to use Ansoft Designer (v2.2) to analyze some structures. I usually analyze using HFSS, but I need quick results that is why I am using the 2.5D simulator of Designer (Planar EM). However, it appears Designer's EM planar simulator is very inaccurate...My S21 goes aboue 0.0 dB...I tried to change the adaptive frequency and the delta, but I always an S21 above 0.0 dB at some frequencies...the circuit I am simualting I have already made and measured...just trying to get Designer to generate accurate results that I can simulate other structures...anyone help?

Designer's PlanarEM solver, formerly known as Ensemble, has a very long heritage and is very reliable - virtually bulletproof when used properly. It sounds like you may be terminating your port with a complex S-parameter file/N-port. This can result in S21 > 1 for passive structures...