Windows phone 8.1 app with out any crash log -

my app has 2 views 1 mantraas list , playmantraview. whenever user clicks on mantra show playmantraview have play button. when user click on play button initiate background audio task , play mantra. when clicks on arrow close play mantra , end background task calling

backgroundmediaplayer.shutdown(); 

which stop background task , move mantras view. here after few seconds app closes without error. have hockey app configured log crashes, don't see crash in hockey app.

could please me nail down error background app start code

private async task startbackgroundaudiotask(string filename)         {             addmediaplayereventhandlers();             log.logdebug("startbackgroundaudiotask - " + filename);             serverinitialized = new autoresetevent(false);             await task.run(() =>             {                 bool result = serverinitialized.waitone(2000);                 log.logdebug("autoresetevent result - " + result);                 if (result == true)                 {                     var message = new valueset();                     message.add(constants.startplayback, new inputmantra()                     {                         mantraid = viewmodel.currentmantra.mantraid,                         reciteid = viewmodel.currentrecitation.recitationid,                         actualcount = viewmodel.currentrecitation.actualcount,                         currentcount = viewmodel.currentrecitation.completedcount,                         filepath = filename,                         mantraname = viewmodel.currentmantra.mantraname                     }.tostring());                     backgroundmediaplayer.sendmessagetobackground(message);                     currentmantraid = viewmodel.currentmantra.mantraid;                  }                 else                 {                     log.logdebug("background audio task didn't start in expected time");                 }             });         } 

when user clicks send message background task

public void stop()         {             applicationsettingshelper.removekey(constants.currentmantra);             currentmantraid = 0;             var message = new valueset();             message.add(constants.stopplayback, constants.stopplayback);             backgroundmediaplayer.sendmessagetobackground(message);         } 

and handle message in background task

void saveandstop()         {             try             {                 if (backgroundtaskrunning)                 {                     backgroundmediaplayer.shutdown();                     backgroundtaskrunning = false;                 }             }             catch (exception ex)             {                 log.logerror("while stopping", ex);             }         } 

will save current state in backgroung task oncancelled method

private void oncanceled(ibackgroundtaskinstance sender, backgroundtaskcancellationreason reason)         {             // time here save state before process , resources reclaimed             log.logdebug("mybackgroundaudiotask " + sender.task.taskid + " cancel requested...");             // set not running             backgroundtaskstarted.reset();             applicationsettingshelper.removekey(constants.currentmantra);             sendtoforeground(constants.backgroundtaskcancelled, "");             applicationsettingshelper.savesettingsvalue(constants.backgroundtaskstate, constants.backgroundtaskcancelled);             //unregister message channel             backgroundmediaplayer.messagereceivedfromforeground -= backgroundmediaplayer_messagereceivedfromforeground;              //remove handlers mediaplayer             backgroundmediaplayer.current.currentstatechanged -= mediaplayer_currentstatechanged;             backgroundmediaplayer.current.mediaended -= mediaplayer_mediaended;             if (backgroundtaskrunning)             {                 backgroundmediaplayer.shutdown();                 backgroundtaskrunning = false;             }             log.logdebug("mybackgroundaudiotask cancel complete...");         }