1: Buy a retail version of arma2 - Steam can be a real head case.
2: look at my post here
3: Use Six updater for all you ace mods as this will update a lot of addons used by ace and have addons from other mods you can also use to update - this is DL from http://dev-heaven.net/projects/six-arma-updater/files
- Also let this application through your firewall or it wont work, it should prompt when running/ launching for the first time.
If you still get stuck you PM me your skype name and i will help you out.