The target principal name is incorrect Error when calling Rest Service

Dear all,

in my asp.net  application, on ASPX page need consume K2 REST service using the code below:

private const string WORKLISTRESTURL = "http://myserver.domain.com:81/K2Services/REST.svc/Worklist/Items";

HttpWebRequest request = WebRequest.Create(WORKLISTRESTURL) as HttpWebRequest;
request.Credentials = CredentialCache.DefaultNetworkCredentials;
XDocument responseDocument;
using (HttpWebResponse response = request.GetResponse() as HttpWebResponse)
using (Stream responseStream = response.GetResponseStream())
using (XmlReader responseReader = XmlReader.Create(responseStream))
{
responseDocument = XDocument.Load(responseReader);
}

When the code is executed, it return error:

Exception Details: System.ComponentModel.Win32Exception: The target principal name is incorrect

Source Error: 
 

Line 25:         // get response Line 26:         XDocument responseDocument; Line 27:         using (HttpWebResponse response = request.GetResponse() as HttpWebResponse) Line 28:         using (Stream responseStream = response.GetResponseStream()) Line 29:         using (XmlReader responseReader = XmlReader.Create(responseStream)) 

While if I directly key in  "http://myserver.domain.com:81/K2Services/REST.svc/Worklist/Items" in browser, it can return data correctly.

What could be wrong with the server/development PC setting?

Thank and regards,

SH