Sound.getBytesLoaded() bug?

Anyone knows whether sound.getBytesLoaded() has a bug?
The codes i am using are:

 
onClipEvent(load)
{
bgSound = new Sound(); 
bgSound.loadSound("abc.mp3");
}
onClipEvent(enterFrame)
{
percentLoaded = Math.round((bgSound.getBytesLoaded()/bgSound.getBytesTotal())*100);
_parent.display = percentLoaded + "%";
trace("loaded: "+ percentLoaded);
}
 
it always tells 100%.
i have trace the bgSound.getBytesLoaded(), but it tells the size same as bgSound.getBytesTotal();
 

Can anyone help me ?

Do you mean locally when you test it? If online, does it happen even after you clear your cache?

both local and online with cache cleared are fail.