Session.SessionID mangler?

Hej,
Har jeg forstået det helt forkert, eller for alle besøgende/brugerer ikke et unikt session.sessionid?

Jeg har fundet den her stump kode som logger alle mine ASP-fejl,
ved at sende 500-100 fejl til filen.
Men nu siger den at den mangler et sessionid?!?!?!

Jeg smider noget af den ind her:
mstrFileName = "C:\W3Sites\minside\www\admin\fejl\log\ErrorLog.txt"

'Kundeid til reff.
mstrCustRefID = Session.SessionID' & "-" & Hour(Now) & Minute(Now) & Second(Now)

Set ASPErr = Server.GetLastError
Response.Clear


LogErrorToFile
'LogErrorToDatabase


Function LogErrorToFile ()
    Dim objFS
    Dim objFile

    On Error Resume Next
    LogError = False

    Set objFS = Server.CreateObject ("Scripting.FileSystemObject")
    If Err.number = 0 Then
        Set objFile = objFS.OpenTextFile (mstrFileName, 8, True)
        If Err.number = 0 Then
            objFile.WriteLine "------------------------------------------------------"
            objFile.WriteLine "* Error At " & Now
            objFile.WriteLine "* CustomerRefID "  & mstrCustRefID           
            objFile.WriteLine "* Session ID " & Session.SessionID
            objFile.WriteLine "* RequestMethod " & Request.ServerVariables("REQUEST_METHOD")
            objFile.WriteLine "* ServerPort " & Request.ServerVariables("SERVER_PORT")
            objFile.WriteLine "* HTTPS " & Request.ServerVariables("HTTPS")
            objFile.WriteLine "* LocalAddr "  & Request.ServerVariables("LOCAL_ADDR")
           
            if Request.ServerVariables("REMOTE_ADDR") = "212.242.199.68" then                  '<-- Hesselvaenget 4 <--**********<---"
                objFile.WriteLine "* HostAddress "  & Request.ServerVariables("REMOTE_ADDR")& " <-- Hesselvaenget 4 <--**********<---"
            else
                objFile.WriteLine "* HostAddress "  & Request.ServerVariables("REMOTE_ADDR")
            end if
           
            objFile.WriteLine "* UserAgent " & Request.ServerVariables("HTTP_USER_AGENT")
            objFile.WriteLine "* URL " &  Request.ServerVariables("URL")
            If ASPErr.ASPCode <> "" Then objFile.WriteLine "* Error #:    " & ASPErr.ASPCode
            If ASPErr.Number <> 0 Then objFile.WriteLine "* COM Error #: " & ASPErr.Number & " (" & Hex (ASPErr.Number) & ")"
            If ASPErr.Source <> "" Then objFile.WriteLine "* Source:      " & ASPErr.Source
            If ASPErr.Category <> "" Then objFile.WriteLine "* Category:    " & ASPErr.Category
            If ASPErr.File <> "" Then objFile.WriteLine "* File:        " & "//" & Request.ServerVariables ("SERVER_NAME") & ASPErr.File
            If ASPErr.Line <> 0 Then objFile.WriteLine "* Line, Column:" & ASPErr.Line & ", " & ASPErr.Column
            If ASPErr.Description <> "" Then objFile.WriteLine "* Description: " & ASPErr.Description
            If ASPErr.ASPDescription <> "" Then objFile.WriteLine "* ASP Desc:    " & ASPErr.ASPDescription
            objFile.WriteLine "* FormData " & Request.Form
            objFile.WriteLine "* HTTP Headers: "
            objFile.WriteLine "*****************************"
            objFile.WriteLine Replace(Request.ServerVariables("ALL_HTTP"),vbLf,vbCrLf)
            objFile.WriteLine "*****************************"
            objFile.WriteLine "------------------------------------------------------" & vbCrLf
            objFile.Close
           
        End If
    End If
End Function