When you are working online, and you try to synchronize the business data in your local database and the remote shared database, an error occurs that prevents the synchronization.
The error is unknown.
Because the error is unknown, the best thing to to do is to stop and then restart the synchronization.
Stop synchronization and restart
On the Business Contact Manager menu, point to Offline and then click Work Offline.
After the offline database has been restored, on the Business Contact Manager menu, point to Offline and then clear the Work Offline option.