Need Actionscript help loading external SWF files

If anyone can help, I would aprpeciate it. I have 3 external SWF files and I would like to load them one at a time. When one is done playing, the next one is loaded and starts playing, but I know I am doing something wrong.

The 3 SWF files are called ad1.swf, ad2.swf, ad3.swf

The main SWF file will load them one at a time.

The first frame in the Actions layer has:
var LastAdNumber=3;
_root.createEmptyMovieClip(“advertisements”,1);
for(ad=1; ad<=LastAdNumber; ad++ ) {
loadMovie(“ad” + ad + “.swf”,advertisements);
}

My problem is not knowing how to stop the SWF file from loading the next movie until the current movie is finished playing till the last frame.

Whatever you can offer to help would be great.

Thanks,
Bruce