When I get calendar invites there is no option to accept them
I have this issue on both my iPad and iPhone. When i get a calendar invite in my inbox (for example an exhange invite *.ics) there is no option to accept the invitation. I can open the event in mail, and view teh details, but there is no way to accept it. The invite also does not show up as an "invitation" in my calendar, althought it does show up in the actual calendar as an event that has not been accepted.
iPhone 4S, iOS 5.1.1