Problems with the time zone to synchronize calendar

[hngaa]

I'm syncing calendar with iphone and have the following problem.

On the local pc I have set the timezone GMT -3 (Argentina), in the Zimbra client default time zone is GMT -3 (Argentina) and the Iphone, I have configured the zone Buenos Aires, Argentina, I guess it's GMT -3.

When I create an event in zimbra, for example:
01 of octubre 1500hs until 1600HS, the iphone is displayed 1400hs to 1500hs ... and reminds me 1 hour before.

Someone can tell me what happens or if there is a bug reported by this incident?

Thank you very much