Preloader not working properly [Flash MX]

I’m using the preloader script from http://www.kirupa.com/developer/mx/percentagepreloader.htm but have come across a problem. The loader works fine when everything is in the movie from the start, jpegs are imported in the timeline and so on.

The thing is that I load a bunch of externally and other items from the library. In those cases the preloader doesn’t run at all, the movie’s just blank until everything is loaded and then it starts. It works ok, except for the preloader.

Anyone have a clue on this or an example of another script that works better?