Anyone know of a great tut for creating an AS2.0 script for extending a MovieClip? Too many problems to post to the forums as of now... would like to try and nail this one down with a little bit of reading first.

I do have one problem someone might be able to help me with...

Code:
class SandBox extends MovieClip {
...
function importImage (newImage:MovieClip) {
    trace( newImage );
    newImage.duplicateMovieClip( "mcSwap", 100 );
    trace( this[ "mcSwap" ] );
    this[ "mcSwap" ]._alpha = 0;
    this.onEnterFrame = newImageHandler;
}
...
}
The trace output shows _level0.mcImageImport (for the trace( newImage ) ) so I know the mc is being passed as a parameter... but the trace( newImage) always comes up undefined... why is the duplicateMovieClip failing?