"Request token or token secret not set in server reply." when attempting to get the request token

I'm using the Twitter API with Signpost and Twitter4J on Android.

My code fails here:

consumer = new CommonsHttpOAuthConsumer(TWITTER_KEY, TWITTER_SECRET);
provider = new DefaultOAuthProvider("https://api.twitter.com/oauth/request_token",
"https://api.twitter.com/oauth/access_token",
"https://api.twitter.com/oauth/authorize");

// Here:
String authUrl = provider.retrieveRequestToken(consumer, CALLBACK);

After a lengthy wait for the API, I get the exception:

Request token or token secret not set in server 开发者_Python百科reply. The service provider you use is probably buggy.

I doubt this is Twitter's problem, so why does this happen and how can I fix it?