users can’t connect to snow leopard server via afp

I've set up a snow leopard server 10.6 on an Xserver. I have promoted my standalone directory to a Master Open Directory. LDAP server is : Running Password Server is : Running Kerberos : is Running I have 6 user accounts. I created Home Directories for each user. I am using Open Directory passwords. [b]The problem I'm having is I can not connect to my server from a client machine! I get a message saying "You entered an invalid username or password" please try again??[/b] Client machine is using Snow Leopard 10.6 I can verify that the the client machine is bound to the server in System Preferences ->Accounts, I see Network Account Server with a green light and the name of my server. DNS is working. I've checked it with chageip -checkhostname, it says that names match, nothing to change. [b]I can login if I enable "Guest Access" in the AFP service[/b]. Kerberos is set for authentication in afp. I suspect it's a Kerberos authentication problem but I can't pinpoint it!! Any ideas/suggestions would be great! Thanks.