Доступ soap веб-сервис с ksoap2

Question

Я пытаюсь вызвать следующий soap метод веб-сервиса в android:

POST /DataService.asmx HTTP/1.1
Host: public.server.de
Content-Type: text/xml; charset=utf-8
Content-Length: length
SOAPAction: "https://server/soa/ping"

<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
  <soap:Header>
    <UserCredentials xmlns="https://soa.server.de/soa/">
      <userName>string</userName>
      <password>string</password>
    </UserCredentials>
  </soap:Header>
  <soap:Body>
    <ping xmlns="https://soa.server.de/soa/">
      <curPingRequest>
        <input>string</input>
      </curPingRequest>
    </ping>
  </soap:Body>
</soap:Envelope>

HTTP/1.1 200 OK
Content-Type: text/xml; charset=utf-8
Content-Length: length

<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap="http://schemas.server.org/soap/envelope/">
  <soap:Body>
    <pingResponse xmlns="https://soa.server.de/soa/">
      <pingResult>string</pingResult>
    </pingResponse>
  </soap:Body>
</soap:Envelope>

Мой подход в Android такой:

String SOAP_ACTION = "https://soa.server.de/soa/ping";
        String METHOD_NAME = "ping";
        String NAMESPACE = "https://soa.server.de/soa/";
        String URL = "https://public.server.de/DataService.asmx";

        try {

            SoapObject Request = new SoapObject(NAMESPACE, METHOD_NAME);
            Request.addProperty("input","test");

            SoapSerializationEnvelope soapEnvelope = new SoapSerializationEnvelope(SoapEnvelope.VER12);
            soapEnvelope.setOutputSoapObject(Request);

            soapEnvelope.dotNet = true;

            ArrayList<HeaderProperty> headerProperty = new ArrayList<HeaderProperty>();

            headerProperty.add(new HeaderProperty("userName", "myUsername"));
            headerProperty.add(new HeaderProperty("password", "myPassword"));

            soapEnvelope.setOutputSoapObject(Request);
            HttpTransportSE transport = new HttpTransportSE(URL);

            transport.call(SOAP_ACTION, soapEnvelope, headerProperty);

            resultString = (SoapPrimitive) soapEnvelope.getResponse();

К сожалению, я всегда получить исключение от сервера:

Код: AppException, Причина: ссылка на объект не была установлена ​​для экземпляра объекта.

Есть идеи?