Address Book woes - Xerox 7845

I cannot add any new device address book entries via the web portal on our WorkCentre 7845.

I get the following message, even though the display name does NOT already exist!  Help!

Next question:  Is there a way that the user can add themselves to the machine by somehow sending an email to the machine?  I swear I heard that was possible!  Is it?  Thanks!