Need help with heelflips.?

This is really frustrating. It seems like when i heelflip, there's to much going on at once. This is what i mean; when i focus on flipping the board, my back foot gets like, 2 inches off the ground. obviously, i can't catch the board with that much clearance. When i focus on lifting my back foot up, i don't flip the board and end up doing an ollie. Any help?