Problem attaching a movie from library

1

I modified the code for the hover captions that is on kirupa.com
The reason i had to try and modify it is because i am generating thumbnails from an xml document and when i want to use the hover caption it is creating the hover on the depth of -16745 or something and all of the thumbnails are on levels 1-10 or however many there are
I can’t seem to figure out how to get the caption to be above the thumbnails.
here is the code i have so far, hope someone can help. but this code so far doesn’t show the caption image that I have in my library
argh


captionFN = function (showCaption, captionText, bName) {
    if (showCaption) {
        //var caption:MovieClip = _root.createEmptyMovieClip("hoverCaption", getNextHighestDepth());
        //trace(this.getDepth());
        this.attachMovie("caption", "cap_mc", this.getNextHighestDepth());
        //cap_mc.caption_txt.text = captionText;
        if ((bName._width+bName._x+cap_mc._width)>Stage.width) {
            xo = -2-cap._width;
            yo = -17;
        } else {
            xo = 2;
            yo = -17;
        }
        cap_mc.onEnterFrame = function() {
            cap_mc._x = _root._xmouse+xo;
            cap_mc._y = _root._ymouse+yo;
            cap_mc._visible = true;
        };
    } else {
        delete hoverCaption.onEnterFrame;
        cap_mc.removeMovieClip();
    }
};