Android : Android: Error while trying to access a .Net Web Service

I have created a small app to access a .Net Web Service

But I get this error from Android

SoapFault - faultcode: 'soap:Client' faultstring: 'System.Web.Services.Protocols.SoapException: Server did not recognize the value of HTTP Header SOAPAction: http://webservice.pollsdb.com/Msgs.
   at System.Web.Services.Protocols.Soap11ServerProtocolHelper.RouteRequest()
   at System.Web.Services.Protocols.SoapServerProtocol.RouteRequest(SoapServerMessage message)
   at System.Web.Services.Protocols.SoapServerProtocol.Initialize()
   at System.Web.Services.Protocols.ServerProtocolFactory.Create(Type type, HttpContext context, HttpRequest request, HttpResponse response, Boolean& abortProcessing)' faultactor: 'null' detail: org.kxml2.kdom.Node@b1ebfe80

does anyone know how to call this service from android?

This is my code

    SOAP_ACTION = namespace + MethodName;

    request = new SoapObject(namespace, MethodName);

    //Adding String value to request object
    request.addProperty("Lg", Lg);
    request.addProperty("Lt", Lt);
    request.addProperty("Cnt", Cnt);

    //request.addProperty("ToUnit", "" + toUnit);

    SetEnvelope();

    //SOAP calling webservice
    androidHttpTransport.call(SOAP_ACTION, envelope);

    //Got Webservice response
    String result = envelope.getResponse().toString();

    return result;