IIS6, ActiveX, and database access

[DavidG]

I'm migrating a legacy intranet site from an IIS5 to IIS6 server. The
site uses ActiveX DLLs to access a SQL database. The problem is that
everything runs fine when hitting localhost from the server, but the
database access appears not to work.

Each page gets the Windows logon name and converts it to an ID:

-----
set obj = server.CreateObject("TN.CClassName")

strUserName = Request.ServerVariables("LOGON_USER")
lngUserID = Session("UserID")

if lngUserID = "" or lngUserID = 0 then

lngUserID = obj.GetUserID(strUserName)
Session("UserID") = lngUserID

if lngUserID = 0 then
Response.Redirect "Errors/UnknownUser.asp?User=" & strUserName
end if

end if
-----

Since a remote request always winds up on the UnknownUser page, I'm
assuming that the DLL is fine but can't get to the database (since the
CreateObject call didn't fail, and since all is well from localhost).

It's obviously a permissions issue, but where?

Thanks,
David