无法使用JSOUP解析某些cookie

Question

我一直在尝试从我在url字符串中指定的页面中捕获响应cookie，但是我只能获取csrftoken，因为sessionid结果为null。我现在真的不知道。我正在使用jsoup 1.8.3

public class asynctask extends AsyncTask<Void, Void, Void > {
    Intent rec = getIntent();
    String password = rec.getExtras().getString("logdatap");
    String username = rec.getExtras().getString("logdatau");




    String csrftoken, sessionid, title, title1, cookies;
    Boolean psws;
    String url = "https://grassi-lc-sito.registroelettronico.com/login/";
    String urll = "https://grassi-lc-sito.registroelettronico.com/news";



    @Override
    protected Void doInBackground(Void... params) {

        try {


            Connection.Response loginForm = Jsoup.connect(url)
                    .userAgent("Mozilla/5.0 (Windows NT 6.3; WOW64; rv:39.0) Gecko/20100101 Firefox/39.0")
                    .method(Connection.Method.POST)
                    .execute();



            Connection.Response cookies = Jsoup
                    .connect(url)
                    .userAgent("Mozilla/5.0 (Windows NT 6.3; WOW64; rv:39.0) Gecko/20100101 Firefox/39.0")
                    .data("username", "536763")
                    .data("password", "499153")
                    .data("btnLogin", "Log in")
                    .method(Connection.Method.POST)
                    .execute();

            Document doc = cookies.parse();



            sessionid = cookies.cookie("sessionid");
            csrftoken = cookies.cookie("csrftoken");




            Connection.Response logtest = Jsoup
                    .connect(urll)
                    .userAgent("Mozilla/5.0 (Windows NT 6.3; WOW64; rv:39.0) Gecko/20100101 Firefox/39.0")
                    .cookie("sessionid", sessionid)
                    .cookie("csrftoken", csrftoken)
                    .method(Connection.Method.GET)
                    .execute();



            Document paglog = logtest.parse();







        }catch (IOException e) {
            e.printStackTrace();}

        return null;
    }

    @Override
    protected void onPostExecute(Void result) {

        Toast.makeText(getApplicationContext(), sessionid, Toast.LENGTH_SHORT).show();

      if (psws){
            Toast.makeText(getApplicationContext(), "nome utente errato", Toast.LENGTH_SHORT).show();

        }
        else {Toast.makeText(getApplicationContext(), "nome utente giusto", Toast.LENGTH_SHORT).show();}