用调用一个SOAP接口,SOAPUI可以获取到,但在c#里实现出错

C#代码如下
string reqstr = "";
//reqstr += " < soapenv:Envelope xmlns:soapenv =\"http://schemas.xmlsoap.org/soap/envelope/\" xmlns:tip=\"http://www.dsc.com.tw/tiptop/TIPTOPServiceGateWay\">";
// reqstr += " <soapenv:Header/>";
// reqstr += " <soapenv:Body>";
// reqstr += " <tip:GetWOData2Request>";
// reqstr += " <tip:request>";
reqstr += "<Request> ";
reqstr += " <Access>";
reqstr += " <Authentication user=\"tiptop\" password=\"tiptop\"/> ";
reqstr += " <Connection application=\"MES\" source=\"192.168.1.1\"/> ";
reqstr += " <Organization name=\"TESTSM\"/> ";
reqstr += " <Locale language=\"zh_tw\"/> ";
reqstr += " </Access> ";
reqstr += " <RequestContent> ";
reqstr += " <Parameter> ";
reqstr += " <Record> ";
reqstr += " <Field name=\"sfb01\" value=\"\"/> ";
reqstr += " <Field name=\"sfb05\" value=\"\"/> ";
reqstr += " <Field name=\"sfb81\" value=\"\"/> ";
reqstr += " <Field name=\"sfb04\" value=\"\"/> ";
reqstr += " </Record> ";
reqstr += " </Parameter> ";
reqstr += " </RequestContent> ";
reqstr += "</Request>";
//reqstr += " </tip:request>";
//reqstr += " </tip:GetWOData2Request>";
//reqstr += " </soapenv:Body>";
//reqstr += "</soapenv:Envelope>";
string _url = "http://192.168.10.26/web/ws/r/aws_ttsrv2_toptest/";
Uri uri = new Uri(_url);
var request = (HttpWebRequest)WebRequest.Create(_url);
//WebRequest request = WebRequest.Create(uri);
request.Method = "POST";
//request.ContentType = "application/x-www-form-urlencoded";
request.ContentType = "text/xml;charset=UTF-8";// "application/xml";
//request.ContentType = "application/x-www-form-urlencoded";
//request.Headers.Add("Accept-Encoding", "gzip,deflate");
request.ProtocolVersion = HttpVersion.Version10;
//request.Timeout = 14000;
byte[] byteData = Encoding.UTF8.GetBytes(reqstr);
int length = byteData.Length;
request.ContentLength = length;
//request.ContentType = "gzip";
System.IO.Stream writer = request.GetRequestStream();
writer.Write(byteData, 0, length);
writer.Close();
var response = (HttpWebResponse)request.GetResponse();
string rp = response.ToString();
运行结果
远程服务器返回错误: (415) Unsupported Media Type。