It should be an IIS setting.
You can try the following VBScript to see all of your 
Request.ServerVariables name and values:
<%@ Language=3DVBScript %>
<%
 option explicit
  Dim strKey
  for each strKey in Request.ServerVariables
    Response.Write strKey & " : " & Request.ServerVariables(strKey) & 
"<br>"& vbCRLF
  next
%>

The value for Request.ServerVariables("LOGON_USER")  will be empty if 
the IIS server or the site, depends on the level of directory Security 
setting,  allow anonymous Access. It shows the client user's logon 
information if "Allow Anonymous Access" is disabled.

Hope this help.
Minny Guo


-----Original Message-----
From: Akthar Hussain [mailto:akthar@e...]
Sent: Tuesday, December 24, 2002 4:18 AM
To: IIS_Applictaions
Subject: [iis_applications] asp and iis issue:
Request.ServerVariables("LOGON_USER")


why does the following script from certain websites but not from others? 
 :-

Request.ServerVariables("LOGON_USER")

is this an iis thing? if so how do i make it work?

thank you in advance to the people who can anser the question.

Kind Regards
Akthar