ActionScript 3 - sound mp3 is not played without error - actionscript-3

Question

Help me, I use Adobe Flash CS3 Professional.
// i have try using this import, but still not work
/*import flash.events.Event;
import flash.media.Sound;
import flash.net.URLRequest;
*/
// here is the code
var req:URLRequest=new URLRequest("music.mp3");
var snd:Sound=new Sound();
snd.load(req);
var chan:SoundChannel=snd.play();// not work using 'snd.play(1);' too
chan.addEventListener(Event.SOUND_COMPLETE, onPlaybackComplete);
function onPlaybackComplete(event:Event){
trace("Musik Complete");
}
When i run the swf or ctrl+enter, the output Musik Complete without any sound played, but the animation still played. For the animation i just create simple twin motion.
i work on this directory
C:/flash/example.fla
C:/flash/example.swf
C:/flash/music.mp3
I have try to import music.mp3 into the library too.
Note: I get the example from my friend(.swf, .fla, .mp3). I play the .swf that shared by my friend and work, but when i try to create by my self, is not work. So, i think music.mp3 was fine to use for Flash. Here is my friend code:
var Audio:musik = new musik();
var chan:SoundChannel = new SoundChannel();
// play
chan=Audio.play();
// stop
chan.stop();
// i am so confuse i run my friend project and work fine (sound and other), if i write from scrap even i write the same code, there is an error, and this the error:
// 1046: Type was not found or was not a compile-time constant: musik.
// 1180: Call to a possibly undefined method musik.

Answer 1

I just watch on youtube, i missing one step.
In library, open properties of music.mp3 and give it class name.
So, we can call the class using this var Audio:musik=new musik();.
Then, create the Sound Channel.
At least, function to play and stop using this:
//play
chan=Audio.play();
// stop
chan.stop();