loadSound False

I have a button that imports an mp3 and is supposed to load completely before playing. Problem is, when I set the loadSound to false it doesn´t play at all, but when I set it to true it does play. Here is the code:


carregarSons = function (som, numeroVolume) {
_root.som1.stop();
_root.som1 = new Sound();
_root.som1.loadSound(som, true);
	som1.onLoad = function(success){
  		this.start(0,999);
  		_root.som1.setVolume(numeroVolume);
	}
}

som2_bt.onPress = function () {
	som = "som/rap1.mp3";
	numeroVolume = 100;
	carregarSons(som, numeroVolume);
}

Any ideas??