the image paths don't have an extension:
http://www.virtualgrandtour.com/gallery_engine/images/aden/1aADENcountry001
update the SQL to return the file_extension column, then edit the image source to add it:
../gallery_engine/images/<?php echo $row_WADApg1_gallery_images['folder_name']; ?>/<?php echo $row_WADApg1_gallery_images['file_prefix']; ?>.<?php echo $row_WADApg1_gallery_images['file_extension']; ?>