Kirupa's xml photogallery, previous btn not working

1

Hello all… i followed the tutorial for kirupa’s xml gallery and for some reason the previous button doesn’t work at all. the next button works fine, but i can’t figure out what’s wrong with the previous button… here’s my code

function loadXML(loaded) {
    if (loaded) {
        xmlNode = this.firstChild;
        image = [];
        description = [];
        total = xmlNode.childNodes.length;
        for (i=0; i<total; i++) {
            image* = xmlNode.childNodes*.childNodes[0].firstChild.nodeValue;
            description* = xmlNode.childNodes*.childNodes[1].firstChild.nodeValue;
        }
        firstImage();
    } else {
        content = "file not loaded!";
    }
}
xmlData = new XML();
xmlData.ignoreWhite = true;
xmlData.onLoad = loadXML;
xmlData.load("images.xml");
/////////////////////////////////////
listen = new Object();
listen.onKeyDown = function() {
    if (Key.getCode() == Key.LEFT) {
        prevImage();
    } else if (Key.getCode() == Key.RIGHT) {
        nextImage();
    }
};
Key.addListener(listen);
previous_btn.onRelease = function() {
    prevImage();
};
next_btn.onRelease = function() {
    nextImage();
};
/////////////////////////////////////
p = 0;
this.onEnterFrame = function() {
    filesize = picture.getBytesTotal();
    loaded = picture.getBytesLoaded();
    preloader._visible = true;
    if (loaded != filesize) {
        preloader.preload_bar._xscale = 100*loaded/filesize;
    } else {
        preloader._visible = false;
        if (picture._alpha<100) {
            picture._alpha += 10;
        }
    }
};
function nextImage() {
    //next line will let it start over again
    p<(total-1) ? p++ : p=0;
    if (loaded == filesize) {
        picture._alpha = 0;
        picture.loadMovie(image[p], 1);
        desc_txt.text = description[p];
        picture_num();
    }
}
function prevImage() {
    if (p>0) {
        p--;
        picture._alpha = 0;
        picture.loadMovie(image[p], 1);
        desc_txt.text = description[p];
        picture_num();
    }
}
function firstImage() {
    if (loaded == filesize) {
        picture._alpha = 0;
        picture.loadMovie(image[0], 1);
        desc_txt.text = description[0];
        picture_num();
    }
}
function picture_num() {
    current_pos = p+1;
    pos_txt.text = current_pos+" / "+total;
}

can someone help me!!! i need this done for a client ASAP! thanks