Okay so A friend recommended that I should do the campaign on legendary, so thats what im doing for my first run through… Things are all going fine I got the first mission complete acheivement before I started because I was playing with a friend, but then I beat the second mission Requim… Theres the commendation…no acheivment. I beat the third mission after 4 hours…theres the commendation…no acheivement. Im signed into live and cant figure this out. Is anyone else having these problems or should I be concerned?