Twitter App - No Authentication Challenges Found

I am writing a Twitter app, and I am encountering an error whenever I attempt to find the user's name from a screen name. I get the following error:

04-10 21:43:57.402: W/System.err(9326): No authentication challenges found

Which means that somehow, I'm not logged in. However, I am able to post, get the timeline statuses and even get the User of each status. I simply cannot do this:

public String getUserFromScreenName(String screenName) throws TwitterException {
m_twitter.verifyCredentials();
return m_twitter.showUser(screenName).getName();
}

The m_twitter.verifyCredentials() PASSES, which means I am authenticated, and the following line somehow I am not.

My m_twitter is defined here:

public void authenticate(String token, String secret) {
m_accessToken = token;
m_accessSecret = secret;

ConfigurationBuilder cb = new ConfigurationBuilder();
cb.setOAuthConsumerKey(m_consumerKey)

[Code] .....

And as I said before, I can read/post/retweet and all that stuff both before AND after this call, but this one simply will not work.