I managed to do a similar thing with The Sky X with Nomad data base (1.1 billion stars), a Lisa spectrograph and my F5.4 300mm Newtonian. I think APT uses the UCA3 which may not have enough star for reliably plate solving the small field available. You can also have problems if a bright star is in the field as with a long enough expose to get enough stars to reliable solve the bright star can swamp the field.
Certainly worth a try.
Regards Andrew