I just figured out that my document class needs to be set to 'dynamic' for it to have dynamic properties. I use this so any instance references on my timeline can be called from its instance name (Timeline.movieClipInstanceName). Everything is good to go, but after setting my document class to dynamic, I place a trace statment in the first frame and nothing happens when I run it from FlashBuilder! Just so you know, this Timeline Class that extends MovieClip is an external SWF that's being loaded into my Flex project through an AS file using the Loader class. Help please, this is holding up my project!