Okay, here's whatcha do.
Go and find game.cfg (The cause of most people's trouble) and open it w/ notepad. Find the gamemode cvar and edit it to your liking then save.
The problem with game.cfg is that it overwrites your server.cfg setting the first time you start your server, so no changes are made until map change or "restart" in console.
So, I suggest either DELETING it OR copying the contents of your server.cfg into it then saving.