I'm not able to unlock RAAM in gears of war 2 multiplayer?

I got Gow 2 for christmas and I beat the game. I then bought GOW1 and beat it. I know that you have to have the"Best served Cold" achievement to unlock RAAM. I got that along with the ones for Minh And A. CARMINE and i still don't have them....Help Plz???????