B screw adjustment yields no pully movement.

[Limeybastard]

When adjusting the B screw either on the smallest or largest cog nothing seems to be moving pully wise. The B screw was my final adjustment after putting my bike together. I can effectively remove the B screw completely and nothing changes. When I tighten then B screw I can see the part behind the Derailleur move, but the hanger pully area doesn't. cheers