Actionscript 3 :: Match Function Type Declaration With Differing Calls?

private function playSound():void
{
_soundChannel = _soundObj.play();
_soundChannel.addEventListener(Event.SOUND_COMPLETE, nextTrack);
}
<s:Button width="35" label=">>" click="nextTrack();"/>

Assuming the nextSound() function looks the same as playSound, typewise... The button click works fine, but the event listener won't call the function because its sending an argument the function isn't expecting. I can change the nextTrack function to be evt:Event, but then the button is sending not enough arguments, and I can't find anything to type it to that will work. I can make a typed function to call the un-typed nextTrack function from the event listener

public function callnextsong(evt:Event):void{
nextTrack();
}