Stream requestStream = request.GetRequestStream(); Error 401 no autorizado

[Luis Esteban Valencia]

Hello. I am making the practice of chapter 6. Biztalk Unleashed its about
sending an HTTP request with a c# webform.

I got this error
Unable to complete web request. Web Exception error: Error en el servidor
remoto: (401) No autorizado.
This is the code of the submit button.
private void btnsubmit_Click(object sender, System.EventArgs e)

{

string requestLocation =
"http://localhost:90/HTTPSender/BTSHTTPReceive.dll";
Status.Text = "";

XmlDocument xmlDocument = new XmlDocument();

xmlDocument.PreserveWhitespace = true;

XmlNode tempXmlNode = xmlDocument.CreateNode(XmlNodeType.Element,
"Activity", "http://que.activity");

xmlDocument.AppendChild(tempXmlNode);

tempXmlNode = xmlDocument.CreateNode(XmlNodeType.Attribute, "type", "");

tempXmlNode.Value = TypeList.SelectedItem.Text;

xmlDocument.DocumentElement.Attributes.Append( (XmlAttribute)tempXmlNode);

tempXmlNode = xmlDocument.CreateNode(XmlNodeType.Element, "Location", "");

tempXmlNode.InnerText = Location.Text;

xmlDocument.DocumentElement.AppendChild(tempXmlNod e);

tempXmlNode = xmlDocument.CreateNode(XmlNodeType.Element, "Timestamp", "");

DateTime now = DateTime.Now;

tempXmlNode.InnerText = now.ToString("s");

xmlDocument.DocumentElement.AppendChild(tempXmlNod e);

tempXmlNode = xmlDocument.CreateNode(XmlNodeType.Element, "Notes", "");

tempXmlNode.InnerText = Notes.Text;

xmlDocument.DocumentElement.AppendChild(tempXmlNod e);

try

{

HttpWebRequest request = (HttpWebRequest)
HttpWebRequest.Create(requestLocation);

request.Method = "POST";

ASCIIEncoding encoding = new ASCIIEncoding();

byte[] requestData = encoding.GetBytes(xmlDocument.OuterXml);

request.ContentType="application/x-www-form-urlencoded";

request.ContentLength = xmlDocument.OuterXml.Length;

Status.Text += "Submitting activity message";

Stream requestStream = request.GetRequestStream();

requestStream.Write(requestData,0,requestData.Leng th);

requestStream.Flush();

requestStream.Close();

HttpWebResponse response = (HttpWebResponse) request.GetResponse();

StreamReader responseData = new StreamReader( response.GetResponseStream());

Status.Text = System.Web.HttpUtility.HtmlEncode( responseData.ReadToEnd()) +
"<br>";

}

catch (WebException wex)

{

Status.Text = "Unable to complete web request. Web Exception error: " +
wex.Message;

}
}