Facebook uses an algorithm to check each image for various details or problems. If it finds a problem, it renders that 'missing image' safe image box. Sometimes, it's a URL issue or content in the image or something else that could prevent the image from showing on some devices. Unfortunately, there's no guaranteed answer as to what's wrong. I noticed on your page that other images are properly appearing in the stream, so it's something about that specific image that Facebook is preventing from being shown.
Sorry I can't be of too much more assistance. All I can suggest is re-saving the image, stripping meta data, resizing it and/or renaming the file so that Facebook's scanner may 'see' it differently.
Thanks,
Alex
Facebook safe image - whats that all about
