How do you get Mongoose Mowdown Triple Kill etc in Halo 3?

i got a triple kill and splattered people in a mongoose and its in matchmaking why don't i get achievement?

How do you get Mongoose Mowdown Triple Kill etc in Halo 3?
the only way to actually get the achievement is to play on lone wolves, and its always easier if you go to the last language on your console settings and play on that, lots of other people are looking for achievements too and they can help you, but you have to tell them before the match begins or start a private chat with all of them because you cant talk during gameplay this should help you with all your problems
Reply:Oh dude that sucks so bad because you need to do it in LONE WOLVES!!! I know it sucks so bad. Its like the worst thing ever. Then millions of people want achievements like you so their are going to be really good people playing LONE WOLVES. Its harder than you think.
Reply:you have to do it in lone wolves. achievements get unlocked only in ranked matches, sadly =(





but congrats on that awesome kill!!
Reply:u gota splat alot of people in one game with the mongoose