Difficulty posting tweets using statuses/update


I am trying to POST tweet using REST API v1.1

I am able to make all of the rest of calls, but facing following error each time in this call “statuses/update”:
{“errors”:[{“message”:“Could not authenticate you”,“code”:32}]}

           String RESOURCE_URL = "https://api.twitter.com/1.1/statuses/update.json";
	OAuthService service = new ServiceBuilder().provider(TwitterApi.class)
	Token accessToken = new Token(token, secret);
	OAuthRequest request = new OAuthRequest(Verb.POST, RESOURCE_URL);
	service.signRequest(accessToken, request);		
	Response response = request.send();