A rushed take-off might be the problem here. Steps 2-4 of this trick tip could help you out. In order to make your feet “stick” to the board, you have to do the movement fluidly. But don’t stress yourself out! You should rather start with some preliminary exercises until you feel safe while ollieing. It is also important to pull your foot up to your board’s nose in a straight manner to prevent it from spinning.
The following descriptions cover skateboard parts that are most prevalent in popular and modern forms of skateboarding. Many parts exist with exotic or alternative constructions. A traditional complete skateboard consists of the deck (often with griptape applied on top to enhance traction), trucks (with urethane bushings), wheels (with sealed bearings), bushings, nuts and bolts to fasten the truck and wheel assembly to the bottom of the deck. Older decks also included plastic parts such as side, tail, and nose guards.

GREAT board. Great design graphics. The boards deck has a real POP to it that makes it GREAT for tricks and a AWESOME beginner board. Only problem is It's super slow and requires a lot of work to maintain speed or to pick up speed period. A simple $20 wheel barring upgrade will fix that and BOOM PERFECT board, PERFECT caved in deck. Only 4 stars because of the lack of speed. I prefer my boards ready out of the box already pre-upgraded, but for the price, no point in complaining. Like almost all new boards, u have to ajust the wheels and the flex of the board to customize it to your liking. You won't regret it. But order it with some "Lucky" or "Red bearings" and your set.
To get higher ollies, I would suggesting resting your back foot on the very end of the tail and the front foot in the middle of the deck to allow for more slide. Popping as hard as you can and catching your board in the groove of the nose with you ankle practically resting in the groove will level the board out in the air. after this initial movement slide you feet back to the bolts on the tail and nose to ensure a clean landing.