Scrolling background problem

Hi,
I’m having a slight problem with a basic flash animation. I’ve made a simple game with a scrolling background that has 2 images. I need the first to scroll into the 2nd, then back into the first, etc…

s38.yousendit.com/d.aspx?id=03AKZE8QAWN8X2X1U5TXUM6MIA

That’s the link to the flash MX file. Could anyone please take a look and offer me some insight or tell me where I’m going wrong with my code? Any help would be much appreciated, thanks. Peace.