Hello,
I just added lightbox according to the Codex guide and adjusted the JS call as per the recommendation of John on version 2.51 here http://omeka.org/forums/topic/lightbox-not-working
However, before and after I updated the call, I was getting this error on my public items show page:
Fatal error: Call to undefined function item_has_thumbnail() ....default/items/show.php
Is there a reason why this would happen with a fresh install of Lightbox?