Recently we developed a custom WordPress site for a client that has an integrated lightbox image gallery. It was an easy plugin installation and activation process. The next step was to add in the images to the media library and then call the shortcode inside the code dialog in the specified page. Everything looked great on thumbnail preview, but when clicking on one to view a larger version the lightbox would not show up. The larger image would preview in a separate window.
First, is to check to see if the lightbox version works together with the WordPress installation and custom theme. WordPress notifies of any updates. Second, check to see if any of the plugins are not compatible with the lightbox plugin, by checking one at a time. If any of them are not compatible, it’s good practice to notify the plugin developer, so they can try to work out a solution for future versions. Third, is to check against any custom codes to see if anything is conflicting. In this particular case it happened to be a jQuery conflict on a particular plugin. By updating these conflicting files it allowed the lightbox to work properly.