* The game may have been updated. Rockstar Games may have released an update that disables cheats, or that changes the way that cheats work. If this is the case, you will need to find a new cheat code for the version of the game that you are playing.
* You may be using the wrong cheat code. Make sure that you are entering the correct cheat code for the game that you are playing, and that you are entering it correctly.
* You may be using a modded version of the game. If you are using a modded version of the game, it is possible that the cheats have been disabled or that they do not work properly.
* You may be using a pirated copy of the game. If you are using a pirated copy of the game, it is possible that the cheats have been removed or that they do not work properly.
If you are still having trouble getting cheats to work, you can try contacting Rockstar Games support for assistance.