I saw this solution in the comments section of Campaign Series Vietnam. If you have installed the game and you can't open any of the scenarios uninstall it and perform a clean re-installation. When you come to the install screen asking for a serial key, copy and paste the following #: SRSR-V141-2278-SRSR-9265.

Error when pick play the escenario

Looks like 'Operational Art of War'... but so many buttons....