Hey, would anyone know why my playstation trophies don’t add up.

For example: on GTA IV one of the trophies states that I need to unlock all of the islands, of which I have done, yet it remains locked. This has happened on a few other games like FIFA 09, Quantum of Solace, Call of Duty etc - Score 20 goals in the arena (I’ve sored like a 1000) but it’s still locked - Kill 50 enemies (I’ve killed like 500 haha), it’s locked as well.

This does not happen on all of the trophies, only a select few, gets a bit annoying though. Any help would be great. Oh, and by the way, I’ve read a few other Questions, and the majority of answers say you need to be signed in to Playstation Network as they have to sync with the server. I wouldn’t have a clue if this is the case, but I’m always signed in when playing a game, so I’m pretty sure that’s not my problem. Thanks.