Assassin's Creed brotherhood sequence 9?

I played assassins creed brotherhood until sequence 8, after that I wanted to take a break, the PS4 can now be turned off, but I can no longer play sequence 9

Why shouldn't you be able to?

Did you end sequence 8 or do you get an error message when starting sequence 9?

I can't start the sequence there I'm supposed to locate the memories in the world but there's nothing on the map