AS3.0 URL Loader and Delay

Download the music list (text file) from the remote directory
I want to make a music list.
After "A codes" have been fully executed, "B codes and below"
Is there any way to run it?
thank you

var n: uint;
var sm:Array = [];
musicList => textField
musicList_btn =>musicList button

//=== A codes =======================================
var request:URLRequest = new URLRequest("http://......./Text/soundList.txt");
var loader:URLLoader = new URLLoader();
loader.load(request);
loader.addEventListener(Event.COMPLETE, completeHandler);

function completeHandler(event:Event):void {
	var str:String = event.target.data;
	sm = str.split(",");  
	sm.sort();
	
	for (var i: uint = 0; i < sm.length; i++) { 
	     musicList.appendText(sm[i]+"\n");
	}
}

//=== B codes ======================================
musicList_btn.addEventListener(MouseEvent.CLICK, musicListSelect);
var musicListOK: Boolean = false;

function musicListSelect(evt: MouseEvent): void {
	musicListOK = !musicListOK;
	if (musicListOK) {
	     musicList.addEventListener(MouseEvent.CLICK, selectMusic);
	} else {
	     musicList.removeEventListener(MouseEvent.CLICK, selectMusic);
	}
}

function selectMusic(e: MouseEvent): void {
	var index: uint = musicList.getLineIndexAtPoint(e.localX, e.localY);
	if (index >= musicList.bottomScrollV) return;
	if ((index != -1) && (index != n)) {
	     n = index;
	     musicPlay(sm[n]);
	}
}

//== next codes =====================
n = int(Math.random() * (sm.length - 1));  //random play
musicPlay(sm[n]);

//=== error ====================
TypeError: Error #2007: Parameter text must be non-null.
	at flash.text::TextField/set text()
	at FiatSound_001_fla::MainTimeline/musicPlay()
	at FiatSound_001_fla::MainTimeline/frame1()

TypeError: Error #1009: Cannot access a property or method of a null object reference.
	at FiatSound_001_fla::MainTimeline/soundCompleteHandler()