I have a 2010 Jack Casady semi-hollow. I am trying to adjust the intonation but seem to be getting nowhere. I can get each string itself as well as the 12th fret harmonic to match intonation but playing the 12th fretted note is registering a bit sharp. I checked on line and read that fretted instruments will have some problems getting all three (open, 12th fretted, and 12th harmonic) to match exactly. So, here are my two questions: 1. Is this really common? and 2. Is it better to have the open and 12th fretted match or open and 12th harmonic? Thanks!