What's wrong with the Marathon Man achievement in Halo 3?

I've gone up to all 7 and accessed them, and went through all the pages for each one, and still no achievement. At first i went back to the 3 levels where their all on, then i went back to them without using rally points, but i still havent gotten the achievement. What the heck is goin on?

wait for a bout ten seconds when you've accessed the terminal it will get all weird a.k.a. it will get 'hacked' after the hacked message there will be a umber out of 7 that is the number of the terminal not how many you've found when the terminal 'hacks' the background goes red and all the letters turn to symbolskrunkfu2

Great...well ill go back when i re-play the campaign and activate them. I'll wait next time :P