i use many methods too login in to joomla admin panel. but the returned value is same az the login page. even when the username and password are correct.
example:
WebClient Client = new WebClient();
System.Collections.Specialized.NameValueCollection Collection =
new System.Collections.Specialized.NameValueCollection();
Collection.Add("username", "--my username--");
Collection.Add("passwd", "--my password--");
Collection.Add("option", "com_login");
Colletion.Add("e0484cdc56d8ccc42187d26a813324ba", "1");
Collection.Add("lang", "");
Client.Proxy = null;
byte[] res = Client.UploadValues(
"http://127.0.0.1/administrator/index.php", "POST", Collection);
textBox1.Text = Encoding.UTF8.GetString(res, 0, res.Length);