VALARM in .ics file

Question

This is the .ics file generated from my C# code and this successfully opens in Outlook and shows the reminder too.

BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//hacksw/handcal//NONSGML v1.0//EN
BEGIN:VEVENT
DTSTART:20131022T130000Z
DTEND:20131023T140000Z
SUMMARY:22Demo1
DESCRIPTION:first demo
LOCATION:Ald
BEGIN:VALARM
TRIGGER:-PT10M
ACTION:DISPLAY
END:VALARM
END:VEVENT
END:VCALENDAR

But when i change the time and supply start time= 09:00 and end time= 10:00 then the .ics file generated is

as below and no reminder in this case is entered when it is opened in Outlook.

BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//hacksw/handcal//NONSGML v1.0//EN
BEGIN:VEVENT
DTSTART:20131022T100000Z
DTEND:20131023T110000Z
SUMMARY:22Demo1
DESCRIPTION:first demo
LOCATION:Ald
BEGIN:VALARM
TRIGGER:-PT10M
ACTION:DISPLAY
END:VALARM
END:VEVENT
END:VCALENDAR

Finally I observed that if the time is given from 13:00 (1:00PM)to 23:00(10:00PM) it is working fine and reminder is added but if i enter time like 09:00(AM) or 11:00(AM) then reminder is not added.

Pls tell where i am going wrong or what i am missing.

Answer 1

In the second case your appointment starts in the past (the first will also soon be in the past) and Outlook will not set a reminder in the past.