Need help with Vugen “Error:The WSDL file "" has an error. (Working copy for / does not exist.)

This is related to my other post “need help with Vugen Error: C interpreter run time error: Error -- Unresolved symbol”

I am running a simple script that use Web Service protocol in Vugen. I this time used the " web_service_call " with the input from <soapenv:Body> which I obtained when call the web service using SOAPUI.

 It is something like this:

 web_set_timeout( "STEP", "180" );

    lr_start_transaction("HDD_IF_getUniqueRepByNcid");

    web_service_call( "StepName=getUniqueRepByNcid_101",
        "SOAPMethod=InterfaceService|InterfaceServicePort|getUniqueRepByNcid", 

"ResponseParam=response",
        "Service=InterfaceService",
        "URL={pEndPoint}",
        "ExpectedResponse=SoapResult",
        "Snapshot=t1352907820.inf",
        BEGIN_ARGUMENTS,

"xml:getUniqueRepByNcid="
    
//    "<ser:getUniqueRepByNcid="
    "<ncid>17294</ncid>"
    "<contextNcid>2000</contextNcid>"
    "<dbEnv>tst</dbEnv>"
    "<withSolr>false</withSolr>",

        END_ARGUMENTS,
        BEGIN_RESULT,
        END_RESULT,
        LAST);

    lr_end_transaction("HDD_IF_getUniqueRepByNcid", LR_AUTO);

I am getting this error:    

 getUniqueRepByNcid.c(19): Error:The WSDL file "" has an error. (Working copy for / does not exist.)

Could someone help me resolve this problem?

Thanks much!