NO SPARTAN OFFICER ACHIEVEMENT ON HALO 3?

ok, this happend to tons of people and like 5 of my friends but...I have the spartan officer pin, 130 exp, 36 highest skill, and no achievement or rouge helmet. Please if someone answers and it works...trust me i have all armor in elete and spartan (including katana) and i will help u on legendary, forge tips, ANYTHING just please help me!