The menu bar is in the way so I can't pull one of my windows there. I had to move the bar up to that monitor as well so it wouldn't be in the way.
I've just tried this in Snow Leopard (10.6.8) without issues...
Menu bar on bottom (primary) screen, secondary screen above and dragging windows between the two is no problem.
To do this, I've used the following configuration under Displays in System Preferences:
Check that your settings match and let us know how you get on.
Maybe a bit tricky, I use Moom and set a keyboard shortcut to move windows between screens which like win key + shift + (left or right) on windows.