No Scrolling within movie clip?

Hello all:

I am trying to modify the Tutorial on this site that contains the scrolling thumbnail XML gallery. I would like to contain the slideshow within a movie clip. While everything works fine when the gallery is created on the main timeline, the thumbnails fail to scroll when placed into a movie symbol. The ActionScript I’m using is the same one that’s found on the tutorial’s site:

If anyone can help me out, I would really appreciate it! Thanks.