Fix JavaScript PrettyPhoto gallery in WordPress

I got a wordpress Page of a client that uses the prettyphoto JavaScript library to show pictures in a lightbox when the thumbnails are clicked. This is default functionality of the theme I’m using. The customer I’m setting this wordpress site up for asked me to implement a “click though” feature for galleries. So when one opens the first image of a gallery and the image opens up big in the lightbox you can navigate to the next/prev image without closing the lightbox in between. A standard feature usually. It’s also a default functionality of the prettyphoto lib which is in use. Generally it’s quite easy to “connect” the images for the lib. They just need to have the same rel attribute value and the lib knows they belong together. I’ve written a few lines of JS to add the rel tag on gallery images and it works perfectly for some galleries - but not for all. For some reason some gallery images are not opening up in the lightbox anymore when my code is applied, although the DOM is (at least in my opinion) 100% the same as for galleries where it works. No JavaScript errors are shown in the console. What I would like to ask you for is to have a look at this and fix it. Please use the word 'gallery' in your bid so I see that you read the whole job description.