Hello, I'm running this code:

loHttp = CREATEOBJECT('MSXML2.XMLHTTP')
m.URL = "https://celcer.sri.gob.ec/comprobantes-electronicos-ws/RecepcionComprobantes?wsdl"
loHttp.Open("POST",m.URL,.F.)
loHttp.Send(ALLTRIM(FILETOSTR("factura.xml")))

but after the SEND command I get loHTTP.status = 500
with the following response text

soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
soap:Body> soap:Fault>
faultcode>soap:VersionMismatch faultcode>
faultstring>No namespace on "factura" element. You must send a SOAP request. faultstring>
soap:Fault> soap:Body>
soap:Envelope>

the file factura XML that I'm sending does match the structure required by the web service, so I don't know whay I'm doing wrong.
Thank you for any help.