[CalDAV / CardDAV] MailClient.Storage.Application.OperationException: Subfolder for folder "XXX" failed due to the following error: OK

I am trying to sync eM client with a Synology CardDAV server.  The server is working and is linked effectively with several Iphones.

I have captured the following from the Log:
6:28:56 PM My Shared Contacts [CalDAV / CardDAV]  Synchronizing subfolders: For folder My Shared Contacts/
6:28:56 PM MyPraxis Shared Contacts [CalDAV / CardDAV]  MailClient.Storage.Application.OperationException: Subfolder synchronization for folder “My Praxis Shared Contacts” failed due to the following error: OK
6:28:56 PM Praxis Shared Contacts [CalDAV / CardDAV]  Synchronizing subfolders: Done

I have checked the URL and the username and password.  What am I missing?