FB feed dialog doesn't show picture thumb in popup

Question

I'm sharing a page created with jquery mobile using the feed dialog API, the resulting pop up shows empty placeholder in chrome and Explorer, instead in firefox doesn't show any placeholder or picture (this would be acceptable). Once shared the post, on user profile page there isn't any image (is not a big problem), the same post on the feed shows the image correctly. Debuging the popup I see this the error:

 Failed to load resource: the server responded with a status of 404 (Not Found) 
 https://fbexternal-a.akamaihd.net/app_full_proxy.php?app=429649223743230&v=1&size=z&cksum=c289f2657db10d1fb3aac895eaef8d53&src=https%3A%2F%2Feasycongress.info%2Ffb%2Flottosmorfia%2Fimages%2F9.jpg

The FB JS used API function is

<script> 
  FB.init({appId: \"$_SESSION[appId]\", status: true, cookie: true});
  function postToFeed$num() {
    // calling the API ...
    var obj = {
      method: 'feed',
      link: '$link',
      picture: '$picture',
      name: '$name',
      caption: '$caption',
      description: '$description'
    };
    function callback(response) {
       document.getElementById('msg').innerHTML = \"Post ID: \" + response['post_id'];
    }
    FB.ui(obj, callback);
  }
</script>
 ";

Any tips?

Answer 1

Looks like the issue is related to https. Using an http:// link for the image the thumb is shown correctly, using https the thumb is not shown. Used in a browser the https link runs fine. The FB liter shows no error on page Any tips?