Outlook 2011 contacts no longer syncing with Apple Contacts

Hi

For a few days it seems Outlook 2011 has stopped syncing the contacts with Apple Contacts - as a result my contact book is no longer updated on my smartphone.

I have checked the sync service in Outlook and they are activated. I event tried to uncheck, close Outlook and check again but nothing happens.

Any idea how I can resolve this ?

Note that syncing between Outlook 2011 and iCal is still working.

Regards

Ch.