I was developing a new website for some months and use the WP Flickr Background plugin. On my local developing system the plugin works fine. But now installed on the server the plugin seems not to be able to connect to Flickr. If I try to add a photo to a gallery nothing happens. I see the status bar working and working but no photo appears. I copied the values of my local MySQL DB of the "wp-flickr-background" field to the one on my server what made the pictures appear in the gallery (in the dashboard, the thumbnails). But these pictures still don't show up on my website and I'm still not able to add more to the gallery.
May this be a problem with PHP or firewall settings? I already checked the differences between my two systems but couldn't find anything.
My server uses an almost fresh Plesk 10.1.1/CentOS installation and a WordPress 3.1 setup with multiple Blogs.