Delegated Administrator Utility can enable a user with either one of the following choices:
Enabling the user by changing the icsStatus to active.
commadmin user modify -A icsStatus:active to enable the user.
Adding the calendar service to the user LDAP entry.
commadmin user modify -S cal
Be sure to use the same method to enable and disable a user. If you tried to enable a user with Delegated Administrator Console, after having disabled the user with Delegated Administrator Utility (changing the icsStatus only), the system will not be able to add service since the user already has service and the user will still be disabled.