"AddressFilter mismatch at the EndpointDispatcher" - wcf

Question

I am trying to extend a classic ASP site by connecting to some WCF web services using SOAP 1.2 messages. So on the client end, there is no binding I am just using XMLHTTP.
I am getting the dreaded "The message with To '' cannot be processed at the receiver, due to an AddressFilter mismatch at the EndpointDispatcher." error.
My client is using a self-signed SSL cert, and the service end has an SSL cert set up as well.
Most of the solutions to this problem involve ServiceBehavior config on the client to turn off the Address Filter but that's not applicable in this case. Any help?
Code
I created a class in VBScript
Class SOAPRequest
Private objXMLHttp, webServiceURL, contentType
Public servicePath, XmlNS, action, SOAPRequest, SOAPResponse
Private Sub Class_Initialize
set objXMLHttp = Server.CreateObject("MSXML2.XMLHTTP")
webServiceURL = Application("Web Service URL")
contentType = "application/soap+xml;charset=UTF-8"
End Sub
Public Function SendRequest
'Open HTTP connection
objXMLHttp.Open "POST", webServiceURL & "/wcf/" & servicePath, False
'Setting request headers
objXMLHttp.setRequestHeader "Content-Type", contentType
objXMLHttp.setRequestHeader "SOAPAction", webServiceURL & "/wcf/" & servicePath & "?wsdl"
dim SOAPEnvelopeStart, SOAPEnvelopeEnd
SOAPEnvelopeStart = "<?xml version='1.0' encoding='utf-8'?><soap:Envelope xmlns:soap='http://www.w3.org/2003/05/soap-envelope' xmlns:urn='" & XmlNS & "'><soap:Header/><soap:Body>"
SOAPEnvelopeEnd = "</soap:Body></soap:Envelope>"
'Send SOAP request
objXMLHttp.Send SOAPEnvelopeStart & SOAPRequest & SOAPEnvelopeEnd
'Get XML Response
SOAPResponse = objXMLHttp.ResponseText
End Function
Public Function Close
Set objXMLHttp = Nothing
End Function
End Class
and then I call it as such
set objSOAP = New SOAPRequest
'set up the request
with objSOAP
.servicePath = "myservice.svc"
.XmlNS = "urn:MyNamespace"
.action = "Action"
.SOAPRequest = "<urn:GetMyData></urn:GetMyData>"
end with
objSOAP.SendRequest