title: How to backdate a post
body: <p>I'm trying to post a message on the timeline in the past and I get the following error:
  "Facebook.FacebookOAuthException : (OAuthException - #100) (#100) You cannot specify a scheduled publish time on a published post"
  I tried to put the current date, a past date or a future date; the result is the same.</p>
  
  <p>I think it may be a problem with the way I obtain the unix timestamp.</p>
  
  <p>Here is the code:</p>
  
  <pre><code>public void PostPostsOnTestUserTimeline()
      {
  
          string userId = "[TEST_USER_ID]"; 
  
          var client = new FacebookClient(accessToken);
          dynamic parameters = new ExpandoObject();
          parameters.message = "Check out this funny article - 39";
  
          parameters.scheduled_publish_time = GetUnixTimestamp(DateTime.Now.AddMinutes(20));
  
          client.Post(string.Format("{0}/feed", userId), parameters);
  
  
      }
  
      private long GetUnixTimestamp(DateTime dateTime)
      {
          double secondsDouble = (dateTime - new DateTime(1970, 1, 1).ToLocalTime()).TotalSeconds;
          return Convert.ToInt64(secondsDouble);
      }
  </code></pre>
  
  <p>Any idea why it crashes? 
  I am writing on the timeline of a test user created at "created_time": "2013-03-05T12:34:15+0000". If I don't specify the scheduled_publish_time, it works fine.</p>
  
  <p>Thank you,
  Iulia</p>