SoundChannel.stop() doesn't seem to stop actually

programming flash
1 
if(_play == false)
{
    _play = true;
   _chan = _song.play(_posx);
}
else
{
    _play = false;
    _chan.stop();
    _posx = _chan.position;
}

Sound pauses, becauseI don’t hear anything, but seems to keep playing behind scenes. So when I resume, sound starts playing from different position.