I'm trying to setup Calendar with my company's exchange account and it keeps displaying the error "calendar needs a valid email address to connect to the exchange account" when trying to connect. Mail and Contacts setup perfectly fine and my calendar was everything was working fine prior to the company upgrading to Exchange 2013. I've read that one issue might be that my Exchange account was hidden from the GAL (Global Address List) but that is not the case. Does anyone have any insight into this issue or know of something I might need to modify? Thanks.