title: Failed to execute 'postMessage' on 'DOMWindow': The target origin provided does not match the recipient window's origin ('null')
body: <p>I have a game in heroku, now I'm trying to make it work in Facebook canvas, but, while it works in Firefox, in Chrome and IE doesn't.</p>
  
  <p>IE shows a warning with a button, when clicking the button, it shows the content.</p>
  
  <p>In chrome, I get this error:</p>
  
  <pre><code>Failed to execute 'postMessage' on 'DOMWindow': The target origin provided ('https://game.herokuapp.com') does not match the recipient window's origin ('null').
  </code></pre>
  
  <p>What's wrong?</p>