If its only coming from the 12th fret, then the 13th has a high spot, or has raised on that side. If you have a hammer with a plastic tip, or a small brass hammer, try gently tapping the fret to seat it properly. If that doesn't work you'll probably need to have a fret level done.

EDIT: Watch this around 2:10 and you'll see what I mean about tapping the fret to seat it. Sometimes a fret will raise out of its slot a bit - http://www.youtube.com/watch?v=iZOqW5S1NVM
Last edited by Matt420740 at Nov 18, 2009,
Quote by denied
Only when the guitar is being fretted. Like I said, only the 12th fret. And harmonics on that fret are clear.

I don't think its a raised fret...Does the fret have to be redone? Or can I do something with the truss rod?

If it was a truss rod problem you'd have buzz in more than one spot. Generally speaking when you don't have enough relief you have buzzing on the first 5 or so frets. If you have too much relief you usually get buzz in the middle positions on the neck.

The fact that its only happening on the treble side of the 12th fret points to a high fret. Its not something you'll be able to see with your eyes. You'll need a straight edge to check for sure.
I saw a guy at my local music store make minor truss rod adjustments and make a one fret buzz go away. I thought the fret needed to be seated as well but it could be the rod
I do sure love me them Gibsons boy