подскажите, почему не работает NetStream.Buffer.Empty?

Код AS1/AS2:
stream_ns.onStatus = function(motion_status:Object):Void {
if (motion_status.code == "NetStream.Buffer.Empty") {
_root.attachMovie('buf_mc', 'buf_mc', 100, {_x:150, _y: 133});
}
if (motion_status.code == "NetStream.Buffer.Full") {
_root.buf_mc.removeMovieClip();
}
}