I am trying to use my Exchange calendar with the iCal app. The account has been added with its respective server details. I am using Airmail to handle the mail side of things, so I have unticked this in the preferences. Only Calendar is marked to sync. The iCal app for some reason, cannot log into or access the Calendar on the server. There is an exclamation mark beside it on the left. Sometimes it asks me for my password, but when entered, still displays this error. I couldn't find much online, any help on this?