rounding thru topline?

I was watching a video of my horse today and she was tracking up nicely but I can't figure out how I can get her to work better over her topline?! I try to not be too restrictive with my rein and get her to bend with my leg. What could I be doing wrong that is preventing her from rounding thru her topline? How can I help make her better?
Thanks for your help!

It's impossible to tell unless we can see the videos.

If I could post I would but video=disc and computer=no disc drive!

Unfortunately without seeing what is going on, there is very little help that can be offered, because there are so many things that could be going on, and even more ways to solve the issues.
Even some photographs of you riding would be more helpful than nothing.

While I can't say for sure, I think that your horse is probably going about with his back hollowed and on the forehand. Try to get him to engage his back and push from behind(:

Can you please explain how one would go about doing this, so the OP can get an idea of what to do.

Gah. Later. I'm half asleep and I just went through a nerve-racking experience in which I was literally quivering violently and struggling to remain aware of what was going on around me. Like I said... later!

She is tracking up nicely and not heavy in the front, just hollow and not using her back much at all and I can't seem to convince her too. I tried doing the long and low stuff but she just seems to ignore me and I can't get her to do that either! :(

Let's see...I am going through the same thing. I am trying to build the topline as well and get the horse to stretch down. For mine, I hold the contact and then use my leg to squeeze him up into the bridle. Once he drops his poll and rounds, I allow him to take the reins while still applying calf pressure. Once his head comes back up I shorten the reins and repeat.

If she is ignoring your calf try using a dressage whip just to tap and encourage her to use her hind end.

Sounds like she is just running around on the forehand. There is a different between running and 'light' in the hand, and going forward off the leg.
Millions of transitions each ride, changes of rein, changes of tempo within each gait etc. will help immensely.
She needs to go off your leg immediately, and slow to your back immediately. Until you have that, you have no hope of getting her 'round'.