使用Signpost for OAuth进行身份验证时，不会检索请求令牌

Question

public class Tumblr {

    public static void main(String args[]) throws OAuthCommunicationException, OAuthMessageSignerException, OAuthExpectationFailedException, OAuthNotAuthorizedException
            {
     OAuthConsumer consumer = new DefaultOAuthConsumer("ConsumerKey",
                                             "ConsumerSecret");


     OAuthProvider provider = new DefaultOAuthProvider(
                "http://www.tumblr.com/oauth/request_token", "http://www.tumblr.com/oauth/access_token",
                "http://www.tumblr.com/oauth/authorize");
     String CallbackURL="http://localhost:8084/FinalTumblr/index.jsp";

       String authUrl =  provider.retrieveRequestToken(consumer,CallbackURL);
     //  String authUrl[] = provider.retrieveRequestToken(OAuth.OUT_OF_BAND);

       System.out.println("AuthUrl.."+authUrl);

         System.out.println("Request token: " + consumer.getToken());
         System.out.println("Token secret: " + consumer.getTokenSecret());




        // create an HTTP request to a protected resource

}
}

EXCEPTION：

"Exception in thread "main" oauth.signpost.exception.OAuthCommunicationException: Communication with the service provider failed: Service provider responded in error: 400 (Bad Request)
    at oauth.signpost.AbstractOAuthProvider.retrieveToken(AbstractOAuthProvider.java:218)
    at oauth.signpost.AbstractOAuthProvider.retrieveRequestToken(AbstractOAuthProvider.java:74)
    at Tumblr.main(Tumblr.java:42)
Caused by: oauth.signpost.exception.OAuthCommunicationException: Service provider responded in error: 400 (Bad Request)
    at oauth.signpost.AbstractOAuthProvider.handleUnexpectedResponse(AbstractOAuthProvider.java:245)
    at oauth.signpost.AbstractOAuthProvider.retrieveToken(AbstractOAuthProvider.java:193)
    ... 2 more
Java Result: 1"

知道这个错误发生的原因吗？