I have just received my new APM 2 and I was all excited about it. I had my plane ready to mount it.

Before mounting the APM I thought let me do the Compass declination and calibration before I fit it.

I can't get the compass to reliably work.

I connect via USB and set the compass to enable, then I do the turning of all axes after I set my home declination. The strange thing is that I get new values every time I do this and all of them are of by a bit...some more some less when looking at the HUD.

Once I disconnect from the Planner and then reconnect the compass is set to "DISABLE" and will show North.

What am I doing wrong?

I am using Mission Planner 1.1.96 and Arduplane 2.40. The APM has not yet been powered by anything but the USB cable.