The Delegates settings were not saved correctly. Cannot activate send-on-behalf-of list - Outlook / Exchange 2010

When a user attempted to delegate reviewer access to his calendar he received the error "The Delegates settings were not saved correctly.  Cannot activate send-on-behalf-of list.  You do not have sufficient permissions to perform this operation on this object."

Turns out the user was attempting to assign delegation permissions based on an Exchange Distribution group.  This should work, as others had done it in the past (myself being one of them).

There are a lot of posts on this, but none of them seemed to help my situation.  They still offer some good information though so here they are: blogs.technet.com and kb2593557.

For my issue I found that converting the distribution group (or rather it's a security group) to a universal group from global.  After making change and then attempting to add again it worked.  This appears to be something that changed potentially with our migration from Exchange 2007 to 2010 several years ago and no one had attempted it since then.