Help with onSoundComplete for embedded WAVs

My problem is a little different than other posted solutions I have seen on here. I have a main movie that loads external swf files which contain an embedded wav file. I find this offers the best compression over external MP3's which are often much bigger. In the external swf I have loaded the WAV file in frame 1 of the timeline. I am having trouble calling out the next external swf file once the WAV has finsihed playing. Can someone please help? Here is my code:

In frame 1 of the external SWF that contains the WAV:

mySound = new Sound(this);
mySound.onSoundComplete = function () {
_root.gotoAndStop("numb") //goes to the next marker in the root movie to externally load the next .swf
}

Is this the right way to do it, or would it be better to run the code in the main movie on the external swf?