Problem with sound.position

Hi, I have a problem with the sound position.

I have a MC with some animations, and I need them to play when a sound is set on an specific position. This what I did:

sonido = new Sound();
sonido.loadSound(“audio/s1.mp3”,true);
this.onEnterFrame = function () {
_root.posicion = sonido.position
if (_root.posicion==5564) {
this.textos_senal.gotoAndStop(2);
}
else if (_root.posicion==10214) {
this.textos_senal.gotoAndStop(3);
}
else if (_root.posicion==16536) {
this.textos_senal.gotoAndStop(4);
}
else if (_root.posicion==24424) {
this.textos_senal.gotoAndStop(5);
}
else if (_root.posicion==28003) {
this.textos_senal.gotoAndStop(6);
}
else if (_root.posicion==36807) {
this.textos_senal.gotoAndStop(7);
}
}

The problem is that sometimes the AS works fine, in other cases, it doesn’t and I don’t know why.

What am I doing wrong? Pleaseee, someone help me with this.