c# - MediaElement position doesn't change -

i want use mediaelement play music, , when music played position, action. code this:

private void button1_click(object sender, routedeventargs e) {     mediaelement1.play();     game_pose_poller.runworkerasync(); // game_pose_poller backgroundworker object     button1.isenabled = false; }  private void game_pose_poller_dowork(object sender, doworkeventargs e) {     while(true)     {         if (mediaelement1.position >= sometime)         {             // 

however found program did nothing @ all. when debugging found mediaelement1.position zero. why 0 after play() called? mediaelement1.source mp3 file included resource in project, , loadedbehavior manual(or play() raise exception).

i've made similar times ago using dispatchtimer instead of backgroundworker. how i've got work:

private dispatchertimer positiontimer;  private void button1_click(object sender, routedeventargs e) {     // create timer check condition (every second example)     positiontimer= new dispatchertimer();     positiontimer.interval = timespan.fromseconds(1);     positiontimer.tick += new eventhandler(positiontimertick);     positiontimer.start();      mediaelement1.play();     button1.isenabled = false; }  void positiontimertick(object sender, eventargs e) {     if (mediaelement1.position.totalseconds >= sometime)     {         //     } }