Forum:I can't get trophies, but I've done quests?

So I have Fallout 3 on PS3 and after completing the game (and several sidequestd) I started over WITHOUT deleting the pre existing file. After searching around this site a bit I discovered Fallout 3 had trophies, so I checked, and what do I find? Nothing. Not even the trophies file. Is my disc flawed? Even when I rented the game prior to it no trophies came up. Do the difficulty levels have something to do with it?