We have a user with two devices runing IOs 5.0.1 and facing calendars don't working in the proper way.

If the user adds an appointment either on the IPAD or the IPHONE the appointment shows on zimbra and on both devices.

If the user makes a change of an appointment on the Iphone it shows ok on the Zimbra, but it doesn't update on the Ipad.

If the user changes an appointment on the Ipad the change it's not shown on the Zimbra neither on the iphone.

We aren't using SSL and we have activated push on the Iphone and on the Ipad.

We are runing FOSS edition and using Caldav connection.

Any suggestion?