agenda one user not in sync

Hi,

One user with a samung Andriod device has since one week troubles with syncing her agenda to the mobile device.
The problem is only for the agenda and is in the 2 directions from GW client to Phone, and from Phone to GW client.
The email and contacts sync is no problem.
We have around 30 users on the Datasync server, this is the first user with such a problem.
We are using Novell Data Synchronizer Versie: 1.2.5 Build: 250