I have the same problem as Anderson with the lockdown - really effective at stopping people, but I can't seem to progress my game from there. Tonight in rolling (against a big heavy guy) I got him in lockdown and he was stuck completely, but even though I got the double underhooks I just couldn't whip him up - when I 'whipped' the leg up, the rest of his body didn't move - his leg just went up in the air a bit - his hips and upper body stayed on me and he was too heavy to bench press off me.
(tried to roll him the other way, but he kept basing his arm - i fought for the arm, but gave up after that continued too long). After what felt like a long time I gave up, released the lockdown and turtled, then fought back to get to into his guard.
What am I doing wrong?