Resetting ScrollRect?

Hey there, Im having an issue with scrollRect. Its all set up and works like a dream, but I cant get it reset properly.

scrollRect moves from a .x of 0 to about 4000.

To reset, I use the following AS

_root.scrollRect.x = 0;

This works fine, and is confirmed by a trace action. However, the scrollRect area doesnt actually move? However, next time the move action is initiated, is goes back to the right place? I dont get it!