How do I save my progress on Splinter Cell Conviction Co-op story mode?

OK SO ME AND MY BROTHER WERE PLAYING THE COOP STORY MODE AND WE BEAT THE FIRST MISSION THAT STARTED OFF SAYING "10 DAYS AGO" AND ONCE WE BEAT IT, WE CAME BACK LATER TO PLAY MISSION 2 AND GUESS WHAT? WHEN WE STARTED OUR GAME BACK UP, WE WERE BACK AT THE BEGINNING OF MISSION 1!!!!! HOW DO WE SAVE THE COOP STORY MODE GAME AFTER BEATING A MISSION? WE WERE SIGNED IN AND EVERYTHING BUT WHEN WE START THE GAME UP IT SAYS UBISOFT PRESENTS....ANY ADVICE?