Wordpress login httpwebrequest

我正在尝试使用httwebrequest和c#登录到wordpress后台，但我做不到。我在网上搜索，发现很多人都有同样的问题，但我找不到正确的解决方案。你可以帮我吗？提前谢谢。

string adres = "http://www.site.com";
CookieContainer cookies = new CookieContainer();
ServicePointManager.Expect100Continue = false;
HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(adres + "wp-admin/");
request.UserAgent = "Mozilla/5.0 (Windows NT 6.1; rv:2.0.1) Gecko/20100101 Firefox/4.0.1";
request.Method = "GET";
request.CookieContainer = cookies;
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
response.Close();

//POST
request = (HttpWebRequest)HttpWebRequest.Create(adres + "/wp-login.php");
request.Method = "POST";
request.CookieContainer = cookies;
string password = haslo;
string loginData = String.Format("loginform=&log=admin&pwd=password&testcookie=1&rememberme=forever&redirect_to=" + Uri.EscapeDataString(adres) + "wp-admin/&wp-submit=" + Uri.EscapeDataString("Zaloguj się"));
 request.ContentType = "application/x-www-form-urlencoded";
 byte[] loginDataBytes = Encoding.ASCII.GetBytes(loginData);
 Stream postData = request.GetRequestStream();
 postData.Write(loginDataBytes, 0, loginDataBytes.Length);
 postData.Close();
 response = (HttpWebResponse)request.GetResponse();
 // NEXT GET
 request = (HttpWebRequest)HttpWebRequest.Create(adres + "/wp-admin/");
 request.Method = "GET";
 request.CookieContainer = cookies;
 HttpWebResponse response1 = (HttpWebResponse)request.GetResponse();
 Stream response1Stream = response1.GetResponseStream();
 StreamReader reader1 = new StreamReader(response1Stream);
 string input1 = reader1.ReadToEnd();
 response1.Close();
 richTextBox1.Text = input1;

我无法登录 - 在第二个"GET"请求后>，我只是得到登录表单，而不是wordpress后台主页。