Ok this is from mission 10, but everytime i press B as stated he hangs from the stairs, ledge, house, whatever u r standing on, and if i press X he always dives on someone else sometimes even a dog never the guard u r chasing it is driving me mad been trying to do this now for an hour.
EDIT: so i did what was suggest i ran down the last alley and ran up the small scaffolding and he got him off there but it didnt count maybe not high enogh so will replay this crappy piece of crap after the main story.
The second objective will take place after the fight. For this to to succeed, you'll need to get to some slight higher ground and then press
while over the target. At the start, I'd simply stay with the target. You'll first run through an alley and some back gardens. Once you exit back onto the street, some guards will block your way and you'll have to turn right.
Running past the blockade, keep up with the target, and he'll start to slow down. This is where you can causally tackle him on the a ground level. If you leave him, he'll turn left down another alley, but this time there will be a set of stairs to your left. Quickly run up these, jump onto the ledge of it and then press
. The target should be close enough for you to tackle him.