jackdaw on "ZenPhoto plugin for WordPress not fully functioning"

Since the beginning of using ZP together with WordPress I use a very small plugin which served me very well untill the latest upgrade of ZP. It is still functioning, but it is not creating the appropriate thumbs anymore. You can see what I mean at the right of this page:
http://www.jacktummers.nl/blog

And now I hope someone can tell me what I have to change in this code to make it work again. I visited the website of the author of this plugin, but I can't get in touch with him (no contact information).

function zenphotos($max=12) {
global $wpdb;

/**************************
* CONFIG *
**************************/

$zen_location = "http://www.jacktummers.nl/collectie/"; /* Set this to the exact location of your zenphoto install. */
$zen_thumb_size = 70; /* Set this to the width you wish the thumbnails to be produced to */

/**************************
* END CONFIG *
**************************/

$zen_output = "";

$zen_images = $wpdb->get_results("SELECT zp_images.filename as zp_filename, zp_images.title as zp_title, zp_albums.folder as zp_folder FROM zp_images as zp_images, zp_albums as zp_albums WHERE zp_images.albumid = zp_albums.id AND zp_images.show = 1 ORDER BY zp_images.id DESC LIMIT 0, $max");

foreach ($zen_images as $zen_image){

$zen_output .='<img src="'. $zen_location .'zp-core/i.php?a='. $zen_image->zp_folder .'&i='. $zen_image->zp_filename .'&w='. $zen_thumb_size .'&h='. $zen_thumb_size .'&cw='. $zen_thumb_size .'&ch='. $zen_thumb_size .'" alt="'. $zen_image->zp_title .'" /> ';

}
echo $zen_output;
}