Problem in getting right rxlevel, rxquality, timing advance

Hi
I m developing an application for windows mobile
and i am using RIL class and GetCellTowerInfo(), for getting the CellID,LAC,MCC,MNC,RxLevel,RxQuality, Timing Advance, i am getting Correct values for CellID, LAC,MCC, MNC. but i am getting zero for RxLevel, RxQuality, Timing Advance...
can anyone help me why i am getting zero for these. if am wrong then what i have to do for the correct values for RxLevel, RxQuality, Timing Advance...

Thanks in Advance

Mobile Developer