Check the number of stars being detected – if that is low (less than 15) then try increasing the image brightness by turning up gain or exposure. If you get to maximum gain and 4s exposures and still do not have enough stars then try adjusting the star detection settings.
If you are getting lots of stars detected but still cannot make progress, check that you really are pointing within 5 degrees of the celestial pole. You can take a snapshot image and upload it to nova.astrometry.net to check.
More hints can be found on the Polar Alignment Troubleshooting page.