You know, you might not have to re-try it. I had this happen to me about a month ago when I was going for the darned pistol badge. I got 5 kills, nothing popped up. Thought maybe it was because I switched kits in the middle and used different pistols. So I stuck with the medic and used that pistol exclusively. Got 5 kills...no badge.....kept going up to 6, 7, and 8 kills.....no badge. So I wondered if there was a problem with that server but all of a sudden, I earned some other badge (can't remember which). So i said "ok, one more darned try". Same thing happened. Got 5 or 6 kills and no badge. I quit the game, pissed off no less, and when I checked the next morning, I had been awarded the badge. I'm guessing I was wasting my time trying those additional times past my first one.
Sorry to hear you're having that problem since I know how mad I got.