Fancybox/lightbox image popups don't work

Hello everyone!

I am having trouble with plugins that make gallery images popup in some fancy boxes. Those plugins are Facebook Vinyl and NextGEN Gallery. They both let me create a gallery of images that can be shown on a page and can show the bigger version of a clicked image in a fancybox/lightbox. The popups work fine on my local version of the site with NextGEN Gallery, but once I transfer the site on a staging server, the popups stop working. As for Facebook Vinyl, they never work, weither I’m on local server or on staging.

I am using a special script to change all the absolute links when I upload it to the staging server, though. The problem could be that the script forgets one place where there is an absolute link for the popups…

What could be causing the popups to not work?

Thank you for your help.