need help in inductor simulations using HFSS

Could anyone do me a favor? I am doing some inductor design using HFSS. I am trying to simulate two design examples in an IEEE letter and another famous Journal. My results are far worse from the published results. For example, one of the published results is a suspended spiral inductor has a peak Q of 70 at 6 GHz, and the corresponding L is 1.35, but my simulation result was only 25 (peak Q) at 2.5GHz with a L of 1.15. I realize the simulation result is a little bit different from the measurement. But it should not be so significant. And normally, the simulation result should better than the measurement result. Anyway, I am suspecting my simulation setup. When I started the inductor research, I consulted the HFSS new customer support. I did the setup based on her comments and she said no problem. But right now, I do think there is some critical problem. Can anyone give me a guidance?