arma 2 OA wont install

[arma 2 OA wont install]

have you tried

exiting steam and right clicking on it and selecting run as administrator

first?

Yes.

I have managed to install it, however when i try to downgrade to 1.62 to play dayz, it doesn't let me. It just reverts to 1.63 because apperently battleye isnt working on the older version

[arma 2 OA wont install]

I use steam and when i click install, it goes through the entire installation thing then at 100% it goes back to the 'install' button on steam, and i cant play.