What am i doing wrong when i Ollie?

i've been trying to get the ollie down for the past week. i have my backfoot on the tail, and my front foot right behind the bolts. i got the steps down. i crouch down, then i pop the tail...but when it comes to dragging my front foot to the nose of the board i get messed up. when i flick (or drag) the board goes high and then it just goes right behind me and i don't even land one foot on it. it's kinda irratating...but there's gotta be something i'm doing wrong. i crouch, pop the tail, but when it comes to flicking my foot to the nose the boards just simply going behind. i usually have my front foot behind the bolts. i've got my heel a small bit off the board. could that be it? please help me out. i want to know what i'm doing wrong. everytime i ollie the board just goes behind me =(