Can’t add laptop to computer list for PHD

New Leopard Server, 30 new Macbooks for teachers. Setting up PHD, which is new to me.! I’ve successfully added 29 laptops via a computer list, and mobile prefs and have been able to sync them with phd management. I have my last one that just won’t go into the computer list. I can see it in ARD, and through shared on the sidebar, but not when I click on the … on the Members tab. Nor can I see it in the computer tab. I’ve tried deleting the contents of the Directory Services folder, even re imaged it. Any suggestions?