title: Inviting friends to my app from c# codebehind
body: <p>I know how to invite friends to my app using the following javascript:</p>
  
  <pre><code>function sendRequestToManyRecipients() {
      FB.ui({method: 'apprequests',
             message: 'My Great Request'
      }, requestCallback);
    }
  </code></pre>
  
  <p>I'm using the following c# code</p>
  
  <pre><code>var fb = new FacebookClient(FacebookSettings.AppId, FacebookSettings.AppSecret);
  dynamic parameters = new ExpandoObject();
  parameters.to = string.Join(",", friendIDs);
  parameters.message = "test vanuit codebehind";
  parameters.to = [USERID];
  
  try
  {
      dynamic result = fb.Post("/apprequests", parameters);
  }
  catch (FacebookApiException ex)
  {
      string msg = ex.Message;
  }
  </code></pre>
  
  <p>But I get the following error: "(GraphMethodException) Unsupported post request."</p>
  
  <p>Does anybody know what I'm doing wrong?</p>
  
  <p>EDIT: Im'm using the C# Facebook SDK 5.3.2.0</p>