Try this, once the ESC is armed (LED solid green) try moving the throttle trim to full up. If I'm using the Esky TX my HB2 won't lift unless I crank the trim. Anymore I just use my Futaba 7CHP with the HB2. That way I can mess around with the throttle and pitch curves.

Also, I've read a few posts where folks have said that the 1500mah li-po's are a bit heavy for the HB2, but that's just hearsay. I'm using 1200mah li-po's and it fly's great!