Defender2015

So i used to play dayz alot a motnh or two ago, but i had to uninstall it to make space for stuff i was doing at the time, so i reinstalled Arma 2 and Arma 2 OA overnight(On steam) and it gives me the error "bad serial number" This pisses me off because it was working just fine before... Would love some help on this. I've already tried re-installing over 3 times. http://puu.sh/3kmCc.jpg (122 kB)