I can't see changes made in iCal when looking at Office365

Hi there

I have a rather specific question I'm hoping someone out there a) understands , and b) knows how to fix!!!

I have a MacBook Air which I use for work and pleasure.

I use iCal for my calendar

I also have an Office365 account for work.

I have successfully added this Exchange calendar (account) to my Preferences in iCal. No issue there - username, account, password all work fine.
When adding work related appointments to my iCal, I put them on this Exchange account/calendar.

However, when going to my Office365 account, these appointments do not appear. And they need to, because I've shared this Exchange calendar with my colleagues.

Can anyone help?

Thanks!