ODST: Mission 10 ???

I just finished ODST for the first time on Legendary Solo Campaign. My guide book says that if I restart the game, Mission 10: Mombasa Streets will open in District 5. This is so players can go back and try to get any achievements they might have missed. The problem is, when I restarted the game, I am sent back to repeat Mission 9: Coastal Highway. Why? How do I open Mission 10? I still need to find the final clue to the game and a few audio files too. Thanks for any help with this. It is appreciated.

if you finished the game and it said you unlocked district than you know the first mission then all those red barriers will be unlocked hoped this helped