With all the Flash tutorials that there are to try out on this site, we?re bound to make some mistakes while working through them?only to backtrack after hours of work to try to find just which mistake in the ActionScripting is causing the Flash movie to work incorrectly.
One way to pinpoint any errors in your scripting is to debug the movie. You can do this by opening your Flash file and then clicking Control->Debug Movie (Ctrl+Shift+Enter).

The Flash movie will publish, and then the Debugger movie will open, displaying information on the movie based on the overall global parameters, as well as on hierarchal levels based on the different items stacked inside.

You can drag the edges of the window to expand it and view the information in each window and tab, and any errors reported as the movie plays.

Another way to access the Debugger without publishing the movie is to click Window->Debugger (Shift+F4).