i have a les paul and its buzzing at the 13th and starting to buzz at the 12th frets. I have taken it to sam ash to get it fixed but they said nothing was wrong with it, but it definately buzzes. could this be something besides the frets or was the guy at sam ash just an asshole?
raise the action at the bridge using the screws beside the saddles at the edge.
Are you sure that you're fretting it properly? If you don't hold the string down properly they can buzz.