java.lang.IllegalStateException: stop() called on uninitialized AudioTrack.

Hi, My app reported the following exception: java.lang.IllegalStateException: stop() called on uninitialized AudioTrack. at android.media.AudioTrack.stop(AudioTrack.java:780) at org.fmod.FMODAudioDevice.run(Unknown Source)

does anyone know, what might be the cause of the exception: My code to play and stop sound is as below:

 public static function PlayAudioClip (audioClip : AudioClip, position : Vector3)
 {
     var gameObject = new GameObject ("OneShotAudio");
     gameObject.transform.position = position;
     gameObject.tag = "SoundGameObject";
     var source : AudioSource = gameObject.AddComponent (AudioSource);
     source.clip = audioClip;    
     source.Play ();
     Destroy (gameObject, audioClip.length);
     return source;
 }
 
 public static function PlaySound(audioClip:AudioClip) 
 {
     if(audioClip==sBonusTimeBGM)
     {
         PlayAudioClip(audioClip, sPlaySoundPosition);
     }
     
     if(GameStat.sSoundEnabled==0)
     {
         return;
     }
     if(!sHasWindowFocus)
     {
         return;
     }
     PlayAudioClip(audioClip, sPlaySoundPosition);
     mSilentTime = 0;
 }
 
 function EnableSound()
 {
     GameStat.sSoundEnabled = 1;
 }
 
 function StopAllSound()
 {
     try{
         var allPrefab : GameObject[] = GameObject.FindGameObjectsWithTag("SoundGameObject");
         for (var aPrefab : GameObject in allPrefab) {
             Destroy(aPrefab);
         }
     }catch(e){
         Debug.Log("StopAllSound(), exception captured");
     }
 }