lower back pain w/ db presses

[getnasty]

I've always hated doing db presses and military presses because they kill my lower back. I'm trying to suck it up and do them because I realize they are a necessity. But right now my back is just killing me. I wear a belt but that doesn't help. Does anyone else have this problem or know why this happens. I can't figure out why, especially since I've been doing squats and/or deadlifts in my program for years. So my lower back should be pretty strong.