Problems with Tiger Clients & Leopard Server

Hello everyone, I'm hoping someone can help shed some light on this as i've spent a few days on this already and I hope i'm not missing anything obvious! We recently purchased an Xserve with Leopard Server software. We were already running Tiger server with Tiger clients. The only thing that is changing is the server (now Leopard) where as the clients are remaining Tiger for now. I'm am pretty sure I have setup the Leopard server correctly. We have an Active Directory for user logons and home folders, and the server as been setup with correct DNS settings, in Advanced mode, as an Open Directory master. LDAP is all up and running also. My problem is that I can login fine on the client Tiger machine, but it does not pull up any of the preferences set in WGM on the Leopard server! Out of interest I built the machine as a Leopard client, bound to AD and LDAP and bam, everything worked fine - preferences, logins and home folders. Went back to Tiger, bound to AD and LDAP and again no preferences!! Is there some backwards compatibility issue for Leopard server and Tiger Clients?? Or... If anyone could please shine some light on this I would be grateful! Thanks in advance!