thickness problem in resonance cavity simulation

I want to simulate resonance cavity to know resonance frequency and Quality factor of the cavity. I found resonance cavity model in model library. It works well. So I move to the next step. To simulate real cavity I made, I adjust thickness to the simple cylindrical cavity. resonance frequency looks still reasonable, but quality factor looks insane. May the problem come from the Impedance boundary condition. There are conduction wall, so field cannot pass through however in outer boundary of conducting wall, Impedance boundary condition applied one more time. Comsol shows really small energy losses. Or, method for calculate Qfactor was wrong.

Are there any way to simulate resonance cavity which have thickness?
Or other way to solve my problem?
Help me please.. I stuck in this problem longer than 1 month...

here is link of my test file
drive.google.com/open?id=0BwLA...TnpFcmEwUVZrc3M&authuser=0