retrieveRequestToken(CommonsHttpOAuthConsumer,CALLBACK_URI) functions throws OAuthCommunicationException


I want to make an android app which will update status in twitter.
I am using signpost-core- and signpost-commonshttp4- jar files.I have given internet uses permission and i have registered app in twitter giving read,write and direct messages permission. Also filled up the callback Url.

code snippet:

private  static  final  String CALLBACK_URI = "app://twitter";
private static final String REQUEST_TOKEN_URL = "";
private static final String ACCESS_TOKEN_URL = "";
private static final String AUTHORIZE_URL = "";

String CONSUMER_KEY = "I4bwezijxf6VwpU8x0tygg";
String CONSUMER_SECRET = "Y6vSdZs3zWBrNogXZWSHKZ590RSXqB5wBwj8vFaayk";

private static  CommonsHttpOAuthConsumer consumer;
private static CommonsHttpOAuthProvider provider;

consumer = new CommonsHttpOAuthConsumer(CONSUMER_KEY, CONSUMER_SECRET);
String authUrl="";

authUrl = provider.retrieveRequestToken(consumer,CALLBACK_URI);

I am totally stuck with this.Please reply.