XML : HTTP Post request of XML file in C#

I have written some code for posting some xml data.
I am sending the request but , its throwing the exception while getting the response.

    string SendingXML = "<? xml version = \"1.0\" encoding = \"utf-8\" ?>< synchroMember >< memberUID >EMAIL:" + email + "</ memberUID >< dynContent >< entry >< key >FIRSTNAME</ key >< value >" + FirstName + "</ value ></ entry >< entry >< key >LASTNAME</ key >< value > " + LastName + "</ value ></ entry >< entry >< key >EMVCELLPHONE</ key >< value >" + phone + "</ value > </ entry >< entry >< key >EMAIL</ key >< value >" + email + "</ value > </ entry ></ dynContent ></ synchroMember >";          string UIURL = paramsIUString;            var request = (HttpWebRequest)WebRequest.Create(UIURL);            var postData = SendingXML;            var data = Encoding.UTF8.GetBytes(postData.ToString());             request.Method = "POST";          request.ContentType = "application/xml";          request.ContentLength = data.Length;          request.Accept = "application/xml";          using (var stream = request.GetRequestStream())          {              stream.Write(data, 0, data.Length);          }          var response = (HttpWebResponse)request.GetResponse();          var responseString = new StreamReader(response.GetResponseStream()).ReadToEnd();    

at, var response = (HttpWebResponse)request.GetResponse();
its throwing the exception

screen shot of the error

Kindly look into the issue.