I have been having trouble as well calibrating the compass on my eTrex 30. I would very slowly progress through the rotations only to get the "failed to calibrate" message on the third (pitch) rotation. I tried many times and even upgraded to the latest firmware but no success. After reading this chain I had an idea and went outside to try it. Instead of moving very slowly, I rotated the device fairly quickly, about 3 seconds per axis. Calibrated the first time I tried it.