Why is my iCal Server Delegation No Longer Available?

I've recently reformatted a Mac Mini Server that was and is running the latest version of OS X Server. It is hosting a private domain for a local network of just a few client machines, and everyone has their own network user account. Yesterday I logged in to one of the users' accounts to update their iCal server delegation preferences, only to find the following message:

"The server doesn't support delgation for this account."

I know that it had been supported only a day earlier, and the delegates who had previously been set up are still visible in the side bar. Any thoughts?

I'm wondering if it has anything to do with the way I have the accounts set up. With the most recent setup I ran into some confusion regarding where network user accounts should be stored. I chose /Server HD/Users, but I've noticed that Disk Utility reports an unexpected ACL on that folder. Perhaps I shouldn't have configured that folder for network users? And maybe that's what Disk Utility is finding, and then users's aren't able to do certain things properly from their accounts? I've also had trouble emptying another user's trash, and deleting some default server calendar from that same account.

If anyone has thoughts, please let me know. And I'd be happy to provide more information if needed. Thanks in advance.

Peace.