Outlook calendar synchronisation problem

Prior to buying Microsoft office 365, I used to use the Microsoft office outlook calendar for all my appointments, and these synchronised to my iPhone via iTunes.

But now I've paid for Microsoft Office 365, this no longer happens and I have to manually input the appointments a second time on my phone calendar.

Why?

I have set up iTunes to synchronise contacts with outlook (which it does), calendars with outlook (which it doesn't) and bookmarks (which it does with Internet explorer).

Getting very frustrated.