I have the Turnigy Trackstar 17.5T ROAR approved motor/ESC combo but am wondering if the operation is correct.

It's set to fwd/brk/rev but I have trouble going into reverse. If I double tap the trigger backwards to get into reverse, it moves 25% of the time. I've tried pausing between trigger taps, slowly depressing the trigger, etc. but nothing changes the outcome. It's completely random when I get reverse. Is this normal?