bigbigdogbig

I just bought and downloaded arma 2 OA and when i went to launch it this and said unable to launch this file. please help. C:\program files(x86)\steam\steamapps\common\arma 2 operation arrowhead\Expansion\dta\lauguagecore.pbo

I just got the ARMA 2 op arrowhead demo on steam, i got this game for the multiplayer mainly but there seems to be very little multiplayer games. Is this because in demo you can only multiplay with other demo players? Or the normal multiplayer scene.