This is normal when you first connect to a new instance. When your instance is created its likely that an older version of Punkbuster is created along with it. Punkbuster automatically updates itself, so this problem should correct itself in 15 minutes.

If you want to update Punkbuster manually run the "pb_sv_update" command in your server's remote console or download PBSetup from Even Balance, upload it to your instance's pb directory, and run it manually from the server. The update process can take about 15 minutes, and after your PB server is updated you shouldn't see this problem again.