How come it works in MX pro and doesn´t in MX?

[Joaquin_win]

Im using this as for two buttons, pause and play:

[AS]
//this is the pause button
on (press) {
_root.myMusicPosition = _root.sonido1.position/1000; _root.sonido1.stop(); sonido1 = new Sound(photo);
}

//this is the play button
on (press) {
_root.sonido1.stop();
_root.sonido1.start(_root.myMusicPosition);
}
[/AS]It works ok in Flash MX pro, but doesn´t work in the MX.
Does somebody know why?

Tanks!