Did your tutorial have you download XML from a server to feed the images to the gallery? Many people forget to check for errors loading the XML file or forget to "do something" once the XML is loaded. Common things not to look for are IOErrorEvent.IO_ERROR or SecurotyErrorEvents warning you the XML you're trying to load is on a different domain (a webserver online) and it doesn't have permission (a crossdomain.xml).
In those situations it can appear like it's doing nothing.
Did you just take the code of the tutorial at the end and try to play it as you went through the tutorial? If you just copy and pasted it all you'lre going to have a hard time isolating the issue. In that case you can always re-do the tutorial until you start to see issues. Then you know where they are.
