It's tied to your character. If you got any of the 45 frags on another character, it won't work. When on the character you allegedly have 45 frags on, go to orbit, click on the dreadnaught so the map comes up, and that map says how many fragments you've found on that specific character. If it's less than 45, then you found some of those frags with a different character, and you'll need to figure out which ones they are and find them again.