Best Answer: I found out that you have a 3rd party plugin installed that comments out document loadScripts that start with //. I have no idea why that is but it's not normal Joomla behavior. For example: $document->addScript('//code.jquery.com/ui/1.10.3/jquery-ui.min.js'); This line of code should display fine on all Joomla sites. Without the "http" or "https", the browser will simply treat it as the same as the site's protocol. However, the plugin on your site changed the normal script call to a commented out script. I made a change in components/com_simgallery/helpers/simgallery.php line 2178 and it's working now. Have a look at that line and you will know what I mean. I suggest finding out what's causing this strange behavior and remove it, as other extensions use the same method to load scripts based on the site's protocol. Also, as you can see, it works for CSS files.