Try this...
Swing with only your right arm (if you're right handed). On your back swing, bring the Move controller back at a decent tempo and at the top of your back swing make sure that the Move controller is pointing past parallel before you begin your down swing.
Make sure that your down swing is at a faster tempo than your back swing. And continue your follow through as you would with a club in your hand.
Try this a few times while increasing the tempo (speed) of the swing.
If you can still not reach 90+% then you probably have a hardware issue as Smiley79 said.