Saitek flight yoke calibration problem

I've been recently experiencing some calibration problems with my saitek pro flight yoke system, the throttle is fine its mainly the yoke giving me problems.When I connect to Squawkbox to fly online the aircraft, with the yoke centered, takes a turn to the left.I have FSUIPC and have read it is the best to control simulation, I've attempted to calibrate my yoke using it, and I think I'm doing it right but I still have the same problem.When I'm not connected on Squawkbox I have no problem whatsoever!Any suggestions??I'm using FS9, Windows 7 64bit.Thanks in advance.