Reminder is not work in default folder

[David lee]

I used as follow coding to send email to outlook client(outlook 2000):

''''''''''''''''''''''''''''''''''''''''''''''
Dim ll As New CDO.Message
Dim bb As New CDO.Configuration

bb.Fields(cdoSMTPServer) = "nc80012"
bb.Fields(cdoSendUsingMethod) = cdoSendUsingPort
bb.Fields.Update

Set ll.Configuration = bb
ll.Fields.Append "urn:schemas:mailheader:x-message-flag", adBSTR _
, -1, _
16, "follow up"

ll.Fields.Append "urn:schemas:httpmail:reply-by", adDate, _
-1, _
16, DateAdd("s", 60, Now)

ll.Fields.Update

ll.To = "(e-mail address removed)"
ll.From = "(e-mail address removed)"
ll.Subject = "test"
ll.TextBody = "aaaaaaaaaa"

ll.Send
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''

When open the email in Inbox folder in outlook2000 in client computer,
the email shown 'Follow up by Mon, 1 Aug 2005 18:15', but system cannot
pop up the reminder window at all times. and after 18:15, the email
shown red font in email list.

Why cannot shown the reminder window?

Thanks,