Adjusting the bridge on my Fender American Jazz Bass

I recently bought a 1998 Fender American Jazz Bass. The person who had it before me has the bridge all messed up so I attempted to fix the action on it. I lowered the action a good deal and now it plays a lot better, but on my A and D strings anything played past the 12th fret dosnt make a note. Can someone who actually knows about this stuff help me with adjusting the bridge??? Thanks!