Here's the story (step-by-step): - Me and one more person were playing the last level. - The game ended. My prediction was that it was because of lag. - We resumed from our last checkpoint. - We finished the level (which means the whole campaign). - The achievements (The ones for completing the last level and the ones for completing the whole campaign on normal, heroic and legendary difficulty) did not pop-up even though we are already back to the main menu and done with the credits. Can anyone explain this? I have already e-mailed bungie of my conern. I am currently awaiting their reply.