get запрос

System.Net.WebRequest reqGET = System.Net.WebRequest.Create("http://yandex.ru");
reqGET.Method = "GET";
System.Net.WebResponse resp = reqGET.GetResponse();
System.IO.Stream stream = resp.GetResponseStream();
System.IO.StreamReader sr = new System.IO.StreamReader(stream);
string s = sr.ReadToEnd();
richTextBox1.Text = s;
An unhandled exception of type 'System.Net.WebException' occurred in System.dll

Additional information: Unable to connect to the remote server