Sometimes the game's copy protection itself can interfere with the trainer's functions. If you have LEGALLY purchased the game, you can visit sites such as megagames . com or gameburnworld . com and download a game 'fix' that will disable the protection and allow the trainer to function properly. Always make a backup of your original files so you can return the game back to it's original state after the necessary cheats have been applied. Just like with trainers, make sure the fix you download matches the version of the game you have.
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