Selfmade Tilt compensated Compass Pitch, Roll, Yaw

Hello,
I try to use the HMC Sensor with my sanguino.cc board.
The library HMC.h work fine but the sensor don't reply to my request with correct value . What Kind of hardware are using ? Are you a complete schematics of connection ? Are you using single or dual power supply ?
What is the normal range of value , I recived data between -13 and + 14 for every axisys .. random ... What'is the problem ?
Regards
Roberto