error when joining server, HELP!!

[webmonkey8]

Hello, I'm getting an error when I try to join a server on Day of Defeat Source:

"Your version does not match the servers..."

What can I do to match the servers? Thanks in advance!

 

[hardhead]

I'm getting the same error message. Is this some scheme to get us to buy the source version Any ideas on what to do? I dumped the game and redownloaded and it's still doing it.