Super-Awful Scrolling Question

I need to get some clouds continuously scrolling across the screen in multiple layers. I already checked out the relevant tutorials for both Flash 5 and Flash MX (there isn’t one for MX 2004)…but when i try to repeat the process with my own hand-drawn instances, it doesn’t seem to work.

For example, I can make Kirupa’s content in the Flash 5 tutorial about scrolling images do what it’s supposed to, but when I hand draw a long line of clouds, convert them into a movie clip, and try to edit them in place, on their own timeline they have reverted back to graphics…i fully admit to having no idea what I’m doing yet with Flash…but this would seem to be a pretty simple process. What am I doing wrong/Can anyone offer advice?