Wait I think I found out a way
. Well what you need to do is put in the arma 2 oa key you want to change it too.. thats step 1.. step 2 load up the arma 2 oa ( it will change it back to normal one ) then minimize the game.. click next on the key changer and then it will say application changed or whatever then go back on registry and its changed and if you joins erver and maximize you dnot get kicked lol
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because its working! but everytime i play ill have to do it
.. ( waiting for someone to post and say what they think.............)