Trouble pulling off a pulloff!

Hello, I'm having trouble executing a pulloff after a bend. ie:

E--------------------------------
B--------------------------------
G------11b(13)b11p9------
D--------------------------------
A--------------------------------
E--------------------------------

I can do the part where you bend up to 13 and back down to 11. But the pulloff doesn't sound off properly. Another example of this same "maneuvere" can be found with AC/DC's "back in black":

E----3p0-------------------------
B--------3p0---------------------
G------------2b(4)b2p0-------
D-----------------------------------
A-----------------------------------
E-----------------------------------

I can do the descending 3-0 pulloffs, but the bend and pulloff part always sounds kinda crummy. Any advice would be greatly appreciated.

Thanks,
Leedogg

Practice.

try focusing on your finger's position before you pull off, then try to get to that position after the bending is done.
Practice slow.