StageVideo problems - actionscript-3

Question

i'm trying some examples founded on the web but don't works...
the code :
package{
import flash.display.Sprite;
import flash.events.StageVideoAvailabilityEvent;
import flash.media.StageVideo;
import flash.events.StageVideoEvent;
import flash.geom.Rectangle;
import flash.media.StageVideoAvailability;
import flash.media.Video;
import flash.net.NetConnection;
import flash.net.NetStream;
import flash.display.DisplayObjectContainer;
public class myStageVideo extends Sprite{
private var stageVideoAvail:Boolean;
private var sv:StageVideo;
public function myStageVideo(container:DisplayObjectContainer){
container.addChild(this);
container.addEventListener(StageVideoAvailabilityEvent.STAGE_VIDEO_AVAILABILITY, onAvail);
}
private function onAvail(e:StageVideoAvailabilityEvent):void{
trace("arrivato a onAvail");
stageVideoAvail = (e.availability == StageVideoAvailability.AVAILABLE);
initVideo();
}
private function initVideo():void{
var nc:NetConnection = new NetConnection();
nc.connect(null);
var ns:NetStream = new NetStream(nc);
ns.client = this;
stageVideoAvail = true;
if(stageVideoAvail){
sv = stage.stageVideos[0];
sv.addEventListener(StageVideoEvent.RENDER_STATE, onRender);
sv.attachNetStream(ns);
trace('available');
}
else{
var vid:Video = new Video(1024, 768);
addChild(vid);
vid.attachNetStream(ns);
trace('not');
}
ns.play('video.mp4');
}
private function onRender(e:StageVideoEvent):void{
sv.viewPort = new Rectangle(0, 0, 1024, 768);
}
public function onMetaData(e:Object):void{
}
public function onXMPData(e:Object):void{
}
}
}
what am I doing wrong? I'm trying from a week, but nothing...
the video.mp4 is in the same folder.
i think 1 error
It is the way in which I add the child to the container