Can't add OS X Server Internet account

Hi,

After installing OS X Server, I'm trying to add the calendar service to my personal MBP, by adding an OS X Server internet account in the System Preferences.

Unfortunately, I get the same error message: ''The user name and password for server.####.com is incorrect.'' despite these being accurate.

I tried creating alternative accounts on OS X Server, but they all give me the same result.

Any thoughts?

Thanks!!!