Multiple sound files combined - problem

Hi - The quick question is - I can only get this to play sound once - then it won’t do it again - why??

I am making a math game for my young kids - it adds numbers from 1 to 5
the variables A & B are randomly generated and make C

The sound reads out a string A + plus + B + equals + C (5 sound files)
It does this the first time the flash is played, however, when the flash movie goes back to the previous frame, and generates new variables - it will not play the sound files anymore.

Can someone help answer why the sound files will only play once…?

Here is the code I am using: - Regards Ash

// setup the sound object
var calcVoice = new Sound(this);
// add a function to “speak” each number
calcVoice.speakNext = function() {
// determine the correct sound file – [ex. “13.mp3”] 2 digits required
var soundURL = “snd_”+answerString.substr(0,2)+".mp3";
// speak the current number
if(answerString.length>0){
this.loadSound(soundURL,true);
// get the next number
answerString = answerString.substr(2);
}
}
// when done, try to speak the next number
calcVoice.onSoundComplete = calcVoice.speakNext;
//add a function to start speaking
/calcVoice.speak = function(answer){
// convert the numerical answer to a string – [ex. “123.456”]
_global.answerString = answer.toString();
// start speaking
this.speakNext();
}
/
calcVoice.speak = function(){
// convert the numerical answer to a string – [ex. 123 = 111213]
//Need to have 2 digits for each no. (99 is +) (98 is =)
var convertString:String = “1”+A.toString()+“991”+B.toString()+“981”+C.toString();
_global.answerString = convertString;
// trace(answerString);
// start speaking
this.speakNext();
}
/*
_global.tempSound=function(){
clearInterval(voiceInt);
calcVoice.onSoundComplete();
}
calcVoice.noSound=function(u){ trace("url: "+u); voiceInt=setInterval(tempSound,30); }
*/
calcVoice.speak();