title: session.isOpened() returns false even if successfully logged in to Facebook
body: <p>I am new to Facebook + native Android. I obediently followed the steps in their website but I keep on receiving "false" result in session.isOpened() method even if I successfully logged in using Facebook. I believe I have set correctly the hash key, package name and class name. Could you please help me what's the problem in this code?</p>
  
  <pre><code>public class MainActivity extends Activity {
  
    @Override
    public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
  
      // start Facebook Login
      Session.openActiveSession(this, true, new Session.StatusCallback() {
  
        // callback when session changes state
        @Override
        public void call(Session session, SessionState state, Exception exception) {
  
            if (session.isOpened()) {
  
            // make request to the /me API
            Request.executeMeRequestAsync(session, new Request.GraphUserCallback() {
  
              // callback after Graph API response with user object
              @Override
              public void onCompleted(GraphUser user, Response response) {
                if (user != null) {
                  TextView welcome = (TextView) findViewById(R.id.welcome);
                  welcome.setText("Hello " + user.getName() + "!");
                }
              }
            });
          }
        }
      });
  
  
    }
  
    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        Session.getActiveSession().onActivityResult(this, requestCode, resultCode, data);
    }
  </code></pre>