Recurrence button greyed out in Outlook 2010 [migrated]

view full story

http://serverfault.com – I recently upgraded my Outlook 2007 to 2010 and I've just noticed the Recurrence button is disabled when creating (or editing) an appointment/meeting. But I can still access the recurrence menu via Ctrl+G. Any ideas on how to enable this button? (HowTos)