Alpha not working right

1

Here is my code that im working on. what im trying to do is have the images fade in when the preloader it complete and have them fade out when it moves on to a next image. and the next image fade and so on… but my picture._alpha<100 its not working correctly… does anyone know what im doing wrong?

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;
        }
    }
    picture.onRelease = function() {
        getURL(link[p], "_blank");
    };
};
function nextImage() {
    if (p<(total-1)) {
        p++;
        if (loaded == filesize) {
            if (picture._alpha<100) {
            picture._alpha += 10;
            }
            //picture._alpha = 0;
            picture.loadMovie(image[p], 1);
            desc_txt.text = description[p];
            picture_num();
            slideshow();
        }
    }
}
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) {
        if (picture._alpha<100) {
            picture._alpha += 10;
            }
            //picture._alpha = 0;
        picture.loadMovie(image[0], 1);
        desc_txt.text = description[0];
        picture_num();
        slideshow();
    }
}