Received authentication challenge is null In Android
===

I am trying to implement OAuth in my Android Application using scribe library, however I am stuck in getting the response as it is giving Exception on line response = request.send(). "Received authentication challenge is null". When I run the same piece of code in my Java test project it runs successfully providing verifier, access code and secret. Please refer my code in Android. Here in our code CyberApi is our custom class containing methods with values for URLs like getAccessTokenEndpoint(), getAuthorizationUrl(), getRequestTokenEndpoint(). Please check the below code and Help in case you can suggest some solution.
    

public class ScribeTest extends AsyncTask<Void, Long, Boolean>{
	
	private static Token accessTokenResult;
	
	@Override
	protected Boolean doInBackground(Void... params)
	{

        ServiceBuilder serviceBuilder = new ServiceBuilder();
        
        CyberAPI api = new CyberAPI();
        
        serviceBuilder.apiKey("key");
        serviceBuilder.apiSecret("secret");
        serviceBuilder.provider(api);
        
        OAuthService service = serviceBuilder.build();
             
        Token requestToken = service.getRequestToken();
        System.out.println("Request Token:-" + requestToken.getToken());
        System.out.println("Request Secret:-" + requestToken.getSecret());
        String authUrl = service.getAuthorizationUrl(requestToken);
        
        OAuthRequest request = new OAuthRequest(Verb.POST, authUrl);
                
		String username = null;
		String password = null; 
		
		username = "user01@mailServer.com";
		password = "password";
		request.addBodyParameter("requestToken", requestToken.getToken());
		request.addBodyParameter("username", username);
		request.addBodyParameter("password", password);		
		
		service.signRequest(requestToken, request);
	    
		Response response = null;    
		try
		{
			response = request.send();
		} 
	    catch (Exception e)
	    {	
			e.printStackTrace();
		}
		
		return null;
    }
	
	
		
