RM Jackal

PLEASE HELP! I can't get this mod to work. I have installed the sniper range mission and have created a folder called "@GMJ_SightAdjustment" in my arma directory and the addons folder within that contains the range cards and the PBO. I have added -mod=@GMJ_SightAdjustment as an extension to my target line so it reads "C:\Program Files\ArmA\arma.exe" -nosplash -mod=@GMJ_SightAdjustment . yet its not there in-game. I really want this to work. Please help! Thanks my email is simontucker84@hotmail.com btw