I'm having a problem with my lightbox

I'm having a problem with my lightbox

I really can't see the problem with my code, but the image will not come up when I click on the thumbnail. Here is my current code. I was pretty much thrown into jQuery after a day of using it so I'm am not at all familiar with it. Any help would be greatly appreciated.

$(document).ready(function() {
    set_up_lightbox();
});

/**
 * set_up_lightbox()
 *
 * This function should create the <div> elements necessary for displaying
 * our lightbox container and our lightbox overlay.
 */
function set_up_lightbox() {
    /**
     * 1.1:  Add two divs to the body of the document:
     *         One for the overlay with ID 'lightbox_overlay'
     *         One for the container with ID 'lightbox_container'
     */
   
    $("body").append($("<div/>").attr("id","lightbox_overlay"));
   
    $("body").append($("<div/>").attr("id","lightbox_container"));
   
   
    /**
     * 1.2:  Hide the two divs we just created, as we don't want them
     *       to display until the user clicks on an image.
     */
     
    $("#lightbox_overlay").hide();
     
    $("#lightbox_container").hide();
     
   
    /**
     * 1.3:  This is the part where we add our thumbnails.  For this example
     *       we want to add one image with src="flowers_thumb.jpg" (our
     *       thumbnail) and add a click method that calls
     *       load_image("flowers.jpg") for the full picture.  This img
     *       should be appended to the div with id "gallery" so that our users
     *       can see it.
     */
     $("#gallery").append( $("<img/>").attr("src", "flowers_thumb.jpg"));
     $("#gallery").click( function() {load_image("flowers.jpg"); });
}

/**
 * load_image(url)
 *
 * This function should fade in the lightbox container and lightbox overlay,
 * displaying only picture given in the 'url' parameter inside the container
 * followed by a 'Close' link for closing the lightbox.
 *
 * The funny syntax of this declaraction is necessary for functions that take
 * parameters.
 */
var load_image = function(url) {

    /**
     * 2.1:  Remove anything that might be in the container already.
     */
    $("#lightbox_container").empty();

    /**
     * 2.2:  Tell the overlay to begin to fade in.
     */
    $("lightbox_overlay").fadeIn("slow");
    /**
     * 2.3:  Append the image to the container.
     */     
    $("#lightbox_container").append( $("<img/>").attr("src", "flowers.jpg"));
    /**
     * 2.4:  Create a clickable "Close" that will call close_image.
     */
     $("lightbox_container").click(function() { close_image(); });
    /**
     * 2.5:  Tell the container to fade in.
     */
     $("lightbox_container").fadeIn("slow");
}

/**
 * close_image()
 *
 * This function should simply dismiss the overlay and container, fading
 * back to the original document.
 */
function close_image() {
    /**
     * 3.1:  Tell the container to fade out.
     */
    $("#lightbox_container").hide();

    /**
     * 3.2:  Tell the overlay to fade out.
     */
     $("#lightbox_overlay").hide();
}