Combobox + mp3 player

Hi,
Im working on a mp3 player and im having some difficulties.

I have the player loading in from xml. I have just added a combobox component so the user can scroll through the tracks and pick one.
What i want is for the selected track to be loaded and play when the user selects it.
At the moment i doesnt. Any help wold be very much apreciated. Here's the code.
The combobox is called - playlist_lb

var s:Sound = new Sound();
s.onSoundComplete = playSong;
s.setVolume(100);

var sa:Array = new Array();

var cps:Number = -1;

var pos:Number;

var xml:XML = new XML();
xml.ignoreWhite = true;
xml.onLoad = function()
{
var nodes:Array = this.firstChild.childNodes;
for(var i=0;i<nodes.length;i++)
{
sa.push(new Song(nodes .attributes.url, nodes.attributes.artist, nodes .attributes.track));
}
playlist_lb.dataProvider=sa;
playSong();
}

xml.load("songs.xml");

function playSong():Void
{
s = new Sound();
s.onSoundComplete = playSong;
s.setVolume(100);
mute.gotoAndStop("on");
if(cps == sa.length - 1)
{
cps = 0;
s.loadSound(sa[cps].earl, true);
}
else
{
s.loadSound(sa[++cps].earl, true);
}
trackInfo.text = sa[cps].artist + " - " + sa[cps].track;
playPause.gotoAndStop("pause");
textPos = 0;
}

function pauseIt():Void
{
pos = s.position;
s.stop();
}

function unPauseIt():Void
{
s.start(pos/1000);
}

// Music Controls

// Play/Pause Toggle
playPause.onRollOver = function()
{
if(this._currentframe == 1) this.gotoAndStop("pauseOver");
else this.gotoAndStop("playOver");
}

playPause.onRollOut = playPause.onReleaseOutside = function()
{
if(this._currentframe == 10) this.gotoAndStop("pause");
else this.gotoAndStop("play");
}

playPause.onRelease = function()
{
if(this._currentframe == 10)
{
this.gotoAndStop("playOver");
this._parent.pauseIt();
}
else
{
this.gotoAndStop("pauseOver");
this._parent.unPauseIt();
}
}

// Next Button
next.onRollOver = function()
{
this.gotoAndStop("nextOver");
}

next.onRollOut = next.onReleaseOutside = function()
{
this.gotoAndStop("next");
}

next.onRelease = function()
{
this._parent.playSong();
}

// Mute Button
mute.onRollOver = function()
{
if(this._currentframe == 1) this.gotoAndStop("onOver");
else this.gotoAndStop("offOver");
}

mute.onRollOut = mute.onReleaseOutside = function()
{
if(this._currentframe == 10) this.gotoAndStop("on");
else this.gotoAndStop("off");
}

mute.onRelease = function()
{
if(this._currentframe == 10)
{
this.gotoAndStop("offOver");
s.setVolume(0);
}
else
{
this.gotoAndStop("onOver");
s.setVolume(75);
}
}