If you were able to post a video of your attempts there are plenty of people on here who could probably tell you exactly how to improve upon what your doing or let you know if there is something you should work on or change, but for the sake of getting you a more immediate answer: When I was learning how to jump w2w I'm sure my major downfall was my approach(edging into the wake) I didn't edge out on my toeside far enough and would then edge as hard as I could towards the wake resulting in to much line tension or not enough which either cause me to not stick the landing by throwing off my balance or just made me fall on my face, also I would crouch and kind of ollie off the wake which didn't do me any good either. So that's an example of what you shouldn't be doing. I would say focus on edging out as far as you can, then when the board flattens out under your feet and you feel the pull of the boat and the line stay consistent slowly start to edge in on your heels, you want to increase the amount you edge as you get closer to the wake and maintain an edge all the way through it with your knees slightly bent, resist at the wake and keep your chest up.
Not sure if this will help but I have a couple videos on youtube of me right after I learned how to jump w2w http://www.youtube.com/watch?v=5BLq2rGrvSE
(don't crouch like I do though it's a bad habit of mine you can see in my second video my body position is better but still not perfect) Hope this helps sooner or later it will click and you'll be on to learning something new, Good Luck!