Android＆amp; FB SDK3：getbirthday（）返回null

Question

我使用Fb SDK3获取他们生日的朋友列表，我已经拥有权限：friends_birthday，user_birthday 但我不能得到朋友的生日（即使是公开的） 这是我的代码：

Request friend_req = Request.newMyFriendsRequest(session,
                    new GraphUserListCallback() {

                        @Override
                        public void onCompleted(List<GraphUser> users,
                                Response response) {
                            // TODO Auto-generated method stub
                            if (response.getError() == null) {
                                for (int i = 0; i < 1; i++) {
                                    Log.i("users", users.get(i).getName());
                                    Log.i("users", users.get(i).getId());
                                    Log.i("Birthday", ""
                                            + users.get(i).getBirthday());
                                }
                            } else {
                                Toast.makeText(Home.this,
                                        response.getError().getErrorMessage(),
                                        Toast.LENGTH_SHORT).show();
                            }}});
            friend_req.executeAsync();