I hope you're not actually passing in values such as "Parameter_name".
Here's a snippet that works with webservicex (not the dotnet "ugly hack" here).
Code:
SoapObject request = new SoapObject("http://www.webserviceX.NET", "GetCountryByCountryCode");
request.addProperty("CountryCode", "US");
SoapSerializationEnvelope envelope = new SoapSerializationEnvelope(SoapEnvelope.VER11);
envelope.dotNet = true;
envelope.setOutputSoapObject(request);
HttpTransport ht = new HttpTransport("http://www.webservicex.net/country.asmx");
ht.call("http://www.webserviceX.NET/GetCountryByCountryCode", envelope);
add(new RichTextField("Response: " + envelope.getResponse()));