whiskey (DayZ)

i pasted all the ad ons from arma 2 into the arma 2 OA folder, but arma 2 does not show up in the expansions when i open up OA, what did i do wrong? i have the steam version, i extracted everything right, i re installed the mod, it says dayz at the top right corner when i start the game, but when i try to join a dayz server it says "you cannot play/edit this mission because some files have been deleted"

i tried this and it still keeps giving me a message that says some necessary files were deleted or something, it has to be the mod becasue its happening to alot of people please i only bought arma 2 CO for this mod, dont let it be a waste of $30 MODS!!!!!!!