sound_player_mute_bt_shuts_up_others_sounds, why ?

In a sound player I have this code assigned to Mute button :

on (press) {
mmkt = new Sound();
mmkt.setVolume(0);

}
on (releaseOutside) {
mmkt = new Sound();
mmkt.setVolume(100);
}

To load the songs :
on (press) {
stopAllSounds();
Vol = 50;
mmkt = new Sound();
mmkt.setVolume(Vol);
loadMovieNum(“flash/soundmc/song2.swf”, 134);
unloadMovie(133);
}

and to stop playing the songs :
on (press) {
stopAllSounds();
unloadMovie(133);
unloadMovie(134);

}

There is another mc (navbarbuttonsounds) on the main time line , that is not controlled by the buttons of sound player ; but if Mute bt is clicked all the sounds of navbarbuttonsounds are shut up together with one of the playing songs ;

is there a way to modify Mute bt code not to shut up the other mc ?
Thank You