Android facebook登录 - 登录完成后需要电子邮件地址，但它总是返回Null

Question

private void logintofb() {
        Utils.showToast("in method", ctx);
        mPrefs = getPreferences(MODE_PRIVATE);
        String access_token = mPrefs.getString("access_token", null);
        long expires = mPrefs.getLong("access_expires", 0);

        if (access_token != null) {
            fb.setAccessToken(access_token);
        }

        if (expires != 0) {
            fb.setAccessExpires(expires);
        }
        if (!fb.isSessionValid()) {
            fb.authorize(this,
            // new String[] { "email", "publish_stream" },new DialogListener() {
                    new String[] { "email" ,"read_stream"}, new DialogListener() {

                        @Override
                        public void onFacebookError(FacebookError e) {
                            // TODO Auto-generated method stub

                        }

                        @Override
                        public void onError(DialogError e) {
                            // TODO Auto-generated method stub

                        }

                        @Override
                        public void onComplete(Bundle values) {
                            // values.get
                             final RequestAsyncTask me;
                            SharedPreferences.Editor editor = mPrefs.edit();
                            editor.putString("access_token",
                                    fb.getAccessToken());
                            editor.putLong("access_expires",
                                    fb.getAccessExpires());
                            editor.commit();
                            Session s=Session.getActiveSession();
                    //      getprofilinfo();
                        //  editor.
                        //  loginToFacebook();
                    // SplashScreen.setStepOneComplete(1);
            //  Session sss=opena
                               me=Request.newMeRequest(s, new GraphUserCallback() {

                                @Override
                                public void onCompleted(GraphUser user, Response response) {
                                    System.out.println("RESPONSEsdf>>>>>>>>>>>>>"+response);
                                      if (user != null) {//HERE USER IS ALWAYS NULL GraphUser user
                                            System.out.println("RESPONSE>>>>>>>>>>>>>"+response);

                                            System.out.println(user.getName());
                                            System.out.println(user.getBirthday());
                                            System.out.println(user.getFirstName());
                                            System.out.println(user.getLastName());
                                            System.out.println(user.getLink());
                                            System.out.println(user.getUsername());
                                            System.out.println(user.getLocation());
                                            System.out.println("facebook user id" + user.getId());
                                           System.out.println(user.asMap().get("email").toString());
//                                  Bundle params = me.getParameters();
//                                  params.putString("fields", "email,name");
//                                  me.setParameters(params);
//                                  me.executeAsync();                                  
                                }
                                }
                            }).executeAsync();
                               Intent i = new Intent(SignUp_activity.this,
                                         MainscreenForChat.class);
                                 startActivity(i);
                                         finish();

                        }

此方法是通过简单的ImageButton点击事件调用的。

但是用户总是把我归还给我......

请帮助!!!!!