MSXML posting SOAP message with Client Certificate

[SP]

I get the following error, I've seen many news forum with similar issue but
never a concrete solution.
anyone have an idea what could be causing this not to work?

msxml4.dll (0x80072F0C)
A certificate is required to complete client authentication

Here's the code:
strPostToURL = "https://cert.here.com/SOAP/"
strCert = "cert.here.com"
strRequest = server.MapPath("/xml/Sample_XML.xml")

set objXMLDocument = CreateObject("MSXML2.DOMDocument.4.0")
objXMLDocument.async = false
objXMLDocument.load(strRequest)

set objSrvHTTP = CreateObject("MSXML2.ServerXMLHTTP.4.0")
objSrvHTTP.setOption 3, strCert
objSrvHTTP.open "POST", strPostToURL, false
objSrvHTTP.setRequestHeader "content-Type","text/xml"
objSrvHTTP.send objXMLDocument <-------------------- Error occurs here

Response.Write objSrvHTTP.responseText
Set objSrvHTTP = Nothing
Set objXMLDocument = Nothing
Response.End

Resources I've looked up and followed that didn't help:
http://support.microsoft.com/default.aspx?scid=KB;en-us;q290761
http://support.microsoft.com/default.aspx?scid=kb;EN-US;q294266
http://support.microsoft.com/default.aspx?scid=kb;EN-US;q301429
http://support.microsoft.com/kb/289481/
http://support.microsoft.com/kb/302080/EN-US/