Why didn`t I get these Halo 3 Achievements?

[Best Answer Ninja]

I did`nt get the Spartan Officer one and I have a Global Ranking of Lieutenant,nor did I get 7 on the 7th one , I got 7 exp on the day after it but it still had the playlist to play on , or does that void it since I did it on the 8th? But I still want my Rogue Helmet!

 

[Drew]

Well, if it wasn't the 7th, then you wouldn't get the achievement, regardless. for the officer one, that is strange. try emailing Bungie.