android-Soap Throws java.io.IOException：HTTP请求失败,HTTP状态：500

java.io.IOException: HTTP request failed, HTTP status: 500

错误,它指向transport.call(SOAP_ACTION,信封);

SoapObject request = new SoapObject(NAMESPACE, METHOD_NAME);                     
//Use this to add parameters                              
request.addProperty("username",usr);
request.addProperty("password",pass);
request.addProperty("backOfficePartnerId",id);

//Declare the version of the SOAP request
SoapSerializationEnvelope envelope = new SoapSerializationEnvelope(SoapEnvelope.VER10);

envelope.setOutputSoapObject(request);

envelope.dotNet = true;

try {
    HttpTransportSE transport = new HttpTransportSE(URL);

    Log.i("bodyout", "" + envelope.bodyOut.toString());

    transport.call(SOAP_ACTION, envelope);      

    // Get the SoapResult from the envelope body.
    SoapObject result = (SoapObject)envelope.bodyIn;
    System.out.println("result IN F TO C::"+result);
}catch(Exception e){
    e.printStackTrace();
}

直到这里都得到了正确的答复.我调试并检查了这些值是否将正确的主体发送出去,对我来说,bodyin为null.