[androidbrasil-dev] Ajuda Web service

Olá pessoal estou tentando conectar a um webservice e da o seguinte
erro:

11-30 08:51:20.468: D/Service(343): -
faultcode: 'soap:Client' faultstring: 'Server did not recognize
the value of HTTP Header SOAPAction: .' faultactor:
'null' detail: org.kxml2.kdom.Node@405303f0

O Web service é feito em .Net e deve retornar um array de string,
estou usando o seguinte codigo:

public class Service {

private static final String METHOD_NAME = "GetCategorias"; //NOME
DO METODO
private static final String NAMESPACE = "http://www.dominio.com.br/
blog.asmx";
private static final String URL = "http://www.dominio.com.br/
blog.asmx";
private Object resultsRequestSOAP;

public String GetPost() {
SoapObject request = new SoapObject(NAMESPACE,
METHOD_NAME);

SoapSerializationEnvelope envelope = new
SoapSerializationEnvelope(SoapEnvelope.VER11);

envelope.dotNet = true;

envelope.setOutputSoapObject(request);

try {

HttpTransportSE androidHttpTransport = new
HttpTransportSE(URL);
androidHttpTransport.call("", envelope);

resultsRequestSOAP = envelope.getResponse();

String[] results = (String[]) resultsRequestSOAP;

return results[0].toString();

} catch (Exception e) {

return e.getMessage();

}
}
}

E Na Actividade chamo ele assim:

Service service = new Service();

String result = service.GetPost();

txTeste.setText(result);