Halo 3 Achievement Help?

I recently played Halo 3 on Xbox Live matchmaking and killed the required 5 enemies with a needler. However, I did not get the achievement.





I killed a team member by accident so would that bug the achievement from working? The stats said I killed 7 people with the needler, and one was the team mate.





Any ideas?

Halo 3 Achievement Help?
It's easier to do on Campaign. Anyways, I'm pretty sure you can only do that on Lone Wolves.
Reply:plus u have to do it on a ranked free for all anyways
Reply:Just play campaign and kill some enemies with the needler instead, easier than trying for it online.
Reply:Do it on campaign mode. Real easy achievement
Reply:Its only on ranked free for all. So if you had a team mate you weremt on the right playlist. Just do it on sierra 117 its very easy.