Need help with Vegeta Blue tech

Hey guys, I'm trying to work on some Vegeta Blue combos, and I can't understand what's happening. Basically, I'm trying to build a combo that ends with his 214M command grab, getting the opponent back down to the ground.

However, no matter what I do, I cannot go from the combo into the command grab (I've seen it done, so I know it's possible). The command grab just pushes me up against the dummy without actually grabbing them, and the training dummy techs out of the combo.

Am I doing it too late? Too early? Why does the enemy teching out of a fall cancel out a command grab? What system am I not understanding here?