Music tracks out of sync in kid's DJ game

programming flash
1

I’m making this mixing game for kids: http://zrreintjes.fatcow.com/flash/game.html
It’s based on one continuous piano track which loops 7 times. Meanwhile you add instruments by dragging the icons onto the boat. It’s supposed to sound cool only it doesn’t because I can’t get the thing to play in sync, even though the tracks are millisecond-tailored to fit the frames exactly. The timeline is subdivided into eight parts per 1 piano-loop, think of them as 8 bars, meant so shorter sounds can be added on the fly, instead of them only joining in at the end of each piano-loop (16 sec each). But already at the end of each of the 7 piano-loops, the sound stops for a split second. I’m thinking it may be due to the length of the script checking which intruments are loaded*. So I’ve not yet tried to add the other sounds on the fly as this would only make the ‘hitches’ more frequent. At the end of the game there’s a demo so you can hear what i could sound like if it worked properly. Sounds cool, huh? But the game doesn’t and I’ve run out of ideas how to fix it. It should be simple, but I suspect the whole thing will have to be built from scratch in a totally different way. The question is how. Anybody got any bright ideas?

  *if (_root.bootje.lading.schelpen_mc_boot2) {
    reply_txt.text="Schelpen!";
    coolTune1 = new Sound (soundLoader1);
    coolTune1.start(0,8);
    coolTune1.loadSound("mp3/schelpen.mp3", true);
    trace("Geluid Schelpen");
}
else{trace("Geluid Schelpen Uit");}

if (_root.bootje.lading.bekken_mc_boot2) {
reply_txt.text=“Bekken!”;
coolTune2 = new Sound (soundLoader2);
coolTune2.start(0,8);
coolTune2.loadSound(“mp3/bekken.mp3”, true);
trace(“Geluid Bekken”);
}
else{trace(“Geluid Bekken Uit”);}

if (_root.bootje.lading.drums_mc_boot2) {
reply_txt.text=“Drums!”;
coolTune4 = new Sound (soundLoader);
coolTune4.start(0,4);
coolTune4.loadSound(“mp3/drums.mp3”, true);
trace(“Geluid drums”);
}
else{trace(“Geluid drums Uit”);}

if (_root.bootje.lading.tweebongos_mc_boot2) {
reply_txt.text=“Tweebongos!”;
coolTune6 = new Sound (soundLoader6);
coolTune6.start(0,4);
coolTune6.loadSound(“mp3/bongo.mp3”, true);
trace(“Geluid Tweebongos”);
}
else{trace(“Geluid Tweebongos Uit”);}

if (_root.bootje.lading.draaitafel_mc_boot2) {
reply_txt.text=“Draaitafel!”;
coolTune8 = new Sound (soundLoader8);
coolTune8.start(0,4);
coolTune8.loadSound(“mp3/draaitafel.mp3”, true);
trace(“Geluid Draaitafel”);
}
else{trace(“Geluid Draaitafel Uit”);}