passing xml document to asp page in biztalk

[BlackBox]

I use vb6 wit folowing code to send XML document to receivestandard.asp page in Biztalk server.

'Get Purchase order from commerce server into xml
Dim oXML3 As New MSXML2.DOMDocument
sFilePath = "c:\POTest\PO.xml"
oXML3.async = False
oXML3.Load sFilePath

'Send PO.XML to Biztalk
Dim XMLHTTP As New MSXML2.XMLHTTP
XMLHTTP.open "Post","

http://ws01943/biztalk/receivepo/receivestandard.asp",

True
XMLHTTP.Send (oXML3.xml)

Why doesn't biztalk react? can anyone send me some examples on how to pass xml to an asp page. How do you code your asp page that receives the xml document?