Assassins Creed Glitch?

Okay I'm in memory block 4 where I get to choose in any order of my targets in cities like acre and damascus but after I go to the assassins bureau and go through all the view points, I cant find any main objective in my map, just save citizens n stuff. I thought after you do all the view points, the main objective comes in the map, currently im in acre and I dont know how to continue on with the game if this is some stupid glitch of some kind or is it that I have to find my own investigation without the map??? Its happening in every city I go to. Oh and I cant access the rich district of the city, proberbly be unlocked later