you need to commit the whole way. you untucked too soon.
you need to pop. which means to use the pressure on the front of your skis to pop off the knuckle.
you need to tuck more.
and after your skis leave the ground, you need to pull them around, and get them under you sooner.
good luck
watch simon dumont do fronts off knuckles.. i copied what he did, and it worked for me.
i cant use youtube at work, otherwise i'd post you a vid.