Issue in inductor modeling

Hey, guys,

I'm modeling inductors by fitting quality factor and inductance, and the fittings are pretty good now. However, I found that although Y parameters (my Q and L are extracted from Y parameters) fit well, the S parameter fittings are nasty (dB(S11) differs about 8dB). This really confuses me, which one should I use to fit my inductor??

Thank you.