title: Delete facebook session cookie from my application on users logout
body: <p>I am working in an application which is using facebook connect to log in the users using their facebook account.</p>
  
  <p>Everything works fine except in the following case:</p>
  
  <ol>
  <li>User logged out from my website and facebook.</li>
  <li>User try to login again in my app.</li>
  </ol>
  
  <p>In this case when the facebook connect popup opens in says "error in the application".</p>
  
  <p>I found that the reason is that the old fbs cookie is not being removed on users logout.
  I have added the code to delete the cookie on logout of my app but the cookie isn't deleted.</p>
  
  <p>Here is my code (using Symfony framework.)</p>
  
  <pre><code>$fbCookie = 'fbs_'.sfConfig::get('app_facebook_application_id');
            $cookie = $request-&gt;getCookie($fbCookie);
            if(!is_null($cookie)){
              setCookie($fbCookie," ", time()-3600);
            }       
  </code></pre>
  
  <p>This doesn't work. The cookie remains the same. The setCookie function returns "1" as expected.</p>
  
  <p>What can be the problem?</p>