Creating continuous movement problems

I took the CCM tutorial posted under the Flash MX section. I completed the tutorial and was stoked to see that it actually worked on my first try. I tried to replicate it again, only this time on a document size of 900px/500px. It’s not working and I’ve messed with a few things to try and fix it. I’ve tried changing the -1000 value; i = 1+_root._xmouse/5 value and so on, but nothing works. Everytime I go to publish the site, my circles simply flash really rapidly in a stationary position. What’s going on? Big ups to anyone who can help?