You only have a limited time to get some intels, like the first one in 'Sins of the Fathers'. Maybe you're missing that one? Or did you use cheat codes while picking one up, because that voids the achievement?
10k 29/03/09 - 100k 17/07/10 - 200k 02/09/11 - 300k 02/02/13 - 400k 20/11/13 - 500k 25/10/14
Achievement #1000: Seek and Destroy - #10000: Fully Evolved - #20000: Data Security
Overachiever: 55 points - 16 Staff Clubs - C/F Clubs 10-5-2