As TheDesigner said, you need to go and download the latest beta patch. 'Bad Version' means that the version of the patch you are using for the game is outdated. Alternatively, you can go and open your Arma II OA folder and scroll down until you see the shortcut called "Launch Arma2 OA Beta Patch". You just double click that, and the game runs automatically and updates the patch for you. This fixed my errors with the beta patch updating; it's pretty quick.