I've just played through the entire campaign again in order to unlock the ghost achievement. I did it all in one sit down, and so didn't go to mission select for any reason, and yet at the end of the game the achievement didn't pop up. I went through my mission stats and each mission says I didn't kill anyone, nor was I detected, so I really don't know how this could be. I know there is the mission 7 area that has caused some people problems, but I made sure I did this bit perfectly, and so this couldn't have affect me. Any idea what may have happened?

I noticed in your thread regarding detection that sleep darting granny rags will void the achievement, how else would I do this section without causing this problem?