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This is also why you cannot calibrate close to the pole. If you draw circles based on DEC around the pole you see that the circumference of these circles gets bigger the further away you are from the pole. Since a guide pulse is the same length wherever you are pointing, a pulse close to the pole results in less 'apparent' movement than a pulse on the equator.
Auto calibration routines need to get a good estimate of a stars movement when sending the pulse. This is called calibration and if you are calibrating close to the pole the absolute movement of the star is not good enough to calibrate.
Your first guiding calibration should be on the meridian within 20 degrees of DEC 0 (the equator). This is what is recommended by PHD2 and my ASIAir pro which includes a guiding feature. Not sure how StarAid overcomes this if it doesn't keep a calibration so YMMV.
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