1. Open active directory users and computers
2. Enable the advanced features in the view menu
3. Search for the account which is in a protected security group
4. Go to Properties / Security / Advanced
5. Check the following box: Include inheritable permissions
6. Retry what you were doing in the Lync Control Panel


More: http://kressmark.blogspot.com.au/2012/02/how-to-lync-enable-domain-admin.html