title: Facebook messager not send message
body: <p>I would like to show my codes but I do not know why my facebook has not got the message.   Thank you very much for help</p>
  
  <pre><code>    HttpURLConnection myConnection = (HttpURLConnection) ((new URL("https://graph.facebook.com/v2.6/me/messages?access_token=the_access_token").openConnection()));
      myConnection.setDoOutput(true);
      myConnection.setRequestProperty("Content-Type", "application/json; charset=UTF-8");
      myConnection.setRequestProperty("Accept", "application/json");      
      myConnection.setRequestMethod("POST");
      myConnection.connect(); 
    JSONObject myTest = new JSONObject();
  
          try {
              JSONObject recipient = new JSONObject();
              recipient.put("id", "martinxxxxxwang");         
              myTest.put("recipient", recipient);
              JSONObject message = new JSONObject();
              message.put("text", "888");         
              myTest.put("message", message);     
              response.getWriter().append(myTest.toString());             
  
          } catch (JSONException e) {
              // TODO Auto-generated catch block
              e.printStackTrace();
          }       
          OutputStream os = myConnection.getOutputStream();
          os.write(myTest.toString().getBytes("UTF-8"));
          os.close();
  </code></pre>
  
  <p>By the way, the content of "myTest" is {"recipient":{"id":"martinxxxxxwang"},"message":{"text":"888"}}.
  And if i try<br>
   "graph.facebook.com/v2.6/me/messages?access_token=token"‌​;, 
  I was told ""error": { "message": "(#100) The parameter user_id is required", "type": "OAuthException", "code": 100, "fbtrace_id": "FEv3jq/ahEq" } }"</p>