Can't play single player on Arma 2: OA. HELP!

[Can't play single player on Arma 2: OA. HELP!]

Thank you all for for the help! I had to delete Day Z. It fixed the problem for now but does this mean that in order for me to play single player I have to get rid of Day Z every time?

[Can't play single player on Arma 2: OA. HELP!]

Are you using any betas?

I currently have DayZ why? Do you think that could be causing a problem?

[Can't play single player on Arma 2: OA. HELP!]

I have both Arma 2 and Arma 2: OA. When I start up OA everything is fine with no error messages. I get to the main menu and all is well except for the option of single player being gray. I can click on every other option from the main menu but single player. I do not know what to do or how to fix it. I have already tried uninstalling and installing again. Also I run it through Steam. Please help!