Get Soap Error Using Microsoft SOAP SDK

I try to invoke a webservice from my program (written in C++, VS6.0 and SoapSDK 3.0).

From SOAPUI I invoke as shown in the image.

I tried to write code based on examples from the inteet as follow.

CoInitialize(NULL);
ISoapSerializerPtr Serializer;
ISoapReaderPtr Reader;
ISoapCoectorPtr Coector;
ISoapError Err;

// Coect to the service
Coector.CreateInstance(__uuidof(HttpCoector30));
Coector->Property["EndPointURL"] = "http://psaljane:8080/CIPSiteWeb/services/MassinissaWebService?wsdl";
Coector->Property["AuthUser"] = "wsuser";
Coector->Property["AuthPassword"] = "WsUseR$1994";
Coector->Coect();

// Begin message
Coector->Property["SoapAction"] = "executeService";
Coector->BeginMessage();

// Create the SoapSerializer
 Serializer.CreateInstance(__uuidof(SoapSerializer30));

// Coect the serializer to the input stream of the coector
Serializer->Init(_variant_t((IUnknown*)Coector->InputStream));

// Build the SOAP Message
Serializer->StartEnvelope("","","");

Serializer->StartBody("");
Serializer->StartElement("executeService", "", "", "impl");

    Serializer->StartElement("Arg0","","","");

        Serializer->StartElement("TYPE_INSTRUMENT","","","");
        Serializer->WriteString("1");
        Serializer->EndElement();

        Serializer->StartElement("NUMERO_INSTRUMENT","","","");
        Serializer->WriteString("4099785");
        Serializer->EndElement();

        Serializer->StartElement("RIB","","","");
        Serializer->WriteString("10001068000000000000415");
        Serializer->EndElement();

    Serializer->EndElement();
Serializer->EndElement();
Serializer->EndBody();
Serializer->EndEnvelope();

// Send the message to the web service
Coector->EndMessage();      

// Read the response
Reader.CreateInstance(__uuidof(SoapReader30));

// Coect the reader to the output stream of the coector
Reader->Load(_variant_t((IUnknown*)Coector->OutputStream),"");

// Display the result   
CString str = (LPCTSTR) Reader->RpcResult->text;    

AfxMessageBox(str, MB_OK);
CoUninitialize();

the AfxMessageBox only shows : is S:Server whicj I guess it is an error send by the server like 'Bad Credential' or other.

So is there a way to get the detailed message of the error?