Halo 3: GLITCH!

Ok guys, i found this stupid glitch in Halo 3 Live play. if you rank up directly from a Gunnery Sergeant Grade 2/3 through Highest Skill IN GLOBAL RANK, and you go DIRECTLY up to a Lieutenant Grade 2/3, you WILL NOT get the Spartan Officer achievement OR THE ROUGE HELMET. I asked the Bungie community about this and said all you need to do to fix it is to RANK UP TO A LIEUTENANT IN A SINGLE MATCHMAKING PLAYLIST. Apparently, this is all not a glitch. apparently, this is the new way to achieve the Spartan Officer Achievement as well as getting the Rouge helmet.