I have a Washburn x-50PROFE with a fixed bridge that I am having trouble intonating. The problem is I have my 5th string's saddle set as short as i can, and the intonation is still flat! I hit the harmonic, in tune, hit the 12th fret, flat. I managed to get the rest of the guitar intonated perfectly but I can't adjust the fifth string as far as I need it to go ¯\(°_o)/¯. Any suggestions ?