I created an appointment in Phoenix (UTC-7) and I am registered in Singapore (UTC+8) so time difference is 15 hours. When I did it for today (30 May 2014) it all worked out ok. But when I did it for June 16 it calculated a time zone difference of only 14 hours and gave me the wrong time for the appointment. I checked that Neither Phoenix nor Singapore use DST. Any ideas why it fails in June?