Facebook SDK会话无法打开

Question

我正在尝试在我的Facebook login应用中添加Android，但Session未被打开。为什么会这样？

import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.util.Log;
import android.view.Menu;
import android.widget.TextView;

import com.facebook.*;
import com.facebook.model.*;

public class MainActivity extends Activity {

@Override
protected 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
        @SuppressWarnings("deprecation")
        @Override
        public void call(Session session, SessionState state, Exception exception) {
            if (session.isOpened()) {
                Log.v("SESSION OPEN","");

                // 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);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

}