title: facebook open graph preview thumbnail image is not showing all of a sudden
body: <p>I know this has been asked several times but i am really puzzled as this just stopped working for my new links last few days. All the old links that are cached just works fine.</p>
  
  <p>I have my meta tags very neat. facebook debug tool does not report any error/warnings. </p>
  
  <p>Here are my meta tags ..</p>
  
  <pre><code>&lt;!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" "http://www.w3.org/TR/REC-html40/loose.dtd"&gt;
  &lt;html&gt;&lt;head&gt;
  &lt;meta http-equiv="content-type" content="text/html; charset=utf-8"&gt;
  &lt;meta property="fb:app_id" content="820998487913242"&gt;
  &lt;meta property="fb:admins" content="param.krish.5"&gt;
  &lt;meta property="fb:admins" content="obtest.obkrish"&gt;
  &lt;meta prefix="og: http://ogp.me/ns#" property="og:site_name" content="Salefrog.in"&gt;
  &lt;meta prefix="og: http://ogp.me/ns#" property="og:type"     content="website"&gt;
  &lt;meta prefix="og: http://ogp.me/ns#" property="og:url" content="http://www.salefrog.in/register_fmp"&gt;
  &lt;meta prefix="og: http://ogp.me/ns#" property="og:title" content="Salefrog.in : Register as a Freelance Marketing Partner (FMP)"&gt;
  &lt;meta prefix="og: http://ogp.me/ns#" property="og:description" content="Register as a FMP. Join us. Get a FMP login and get paid as you earn credit points. More details in your login upon registration."&gt;
  &lt;meta property="og:image" content="http://www.salefrog.in/img/fmp-picture.jpg"&gt;
  &lt;meta property="og:image:type" content="image/jpeg"&gt;
  &lt;meta property="og:image:width" content="250"&gt;
  &lt;meta property="og:image:height" content="250"&gt;
  &lt;meta name="title" content="Salefrog.in : Register as a Freelance Marketing Partner (FMP)"&gt;
  &lt;meta name="description" content="Register as a FMP. Join us. Get a FMP login and get paid as you earn credit points. More details in your login upon registration."&gt;
  &lt;link rel="image_src" href="http://www.salefrog.in/img/fmp-picture.jpg"&gt;
  &lt;/head&gt;&lt;/html&gt;
  </code></pre>
  
  <p>Facebook debug tool tells me that it picks up an image but the image preview is not just there at all (looks to be hidden) as shown below.</p>
  
  <p><img src="https://i.stack.imgur.com/vElLJ.png" alt="enter image description here"></p>
  
  <p>When i click that "blank" space against the "og:image" , it opens up the image in a separate window so why does not it show up the preview image in the debug tool ?</p>
  
  <p>I attempted changing the picture to different sized one's like 250x250, bigger etc. but nothing really helped. When i place one of the old cached images in the meta tag, it shows up that image. This tells me that old cached images are just fine but the newer images are not showing at all, for some reasons. </p>
  
  <p>I tested using the link <a href="http://www.salefrog.in/register_fmp" rel="nofollow noreferrer">http://www.salefrog.in/register_fmp</a> in the debug tool. If you guys can find some error, do let me know as it would really help me save time than i break my head to fix it all by myself. </p>