Although its really hard to say, check these 3 things:
Pop: When you pop, make sure that the rope is close to your hips, and you have BOTH hands on it.
Pull: After leaving the wake, pull the rope with both hands to your back hip, make sure you don't let one off too soon!
Pass: When you pass the handle, keep it as tight to your lower back as possible. This will help you keep handle control. My best guess is that this is what you are screwing up if you are nosing it...a handle pass with extended arms is a surefire way to add a ton of tension to the trick, and pitch the board for a bad nose landing.
Good luck, and post some video/pictures if you need more help!