ERROR: System.Web.Services.Protocols.SoapException: Server did not recognize the value of HTTP Header SOAPAction: 
indirizzo namespace/GetFolderContent 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.ServerProtocol.SetContext(Type type, HttpContext context, HttpRequest request, HttpResponse response) 
at System.Web.Services.Protocols.ServerProtocolFactory.Create(Type type, HttpContext context, HttpRequest request, HttpResponse response, Boolean& abortProcessing)