i would hazard a guess that the machine you are using does not have BIND9 or any sort of DNS server currently configured on it. Even if you set up LDAP you need the network and DNS to be able to point where that stuff is so the server can respond. This guide has SAMBA also but look through how and where all the domain stuff is set up, you will need it configured rather SAMBA or LDAP (or both) is in use. KERBEROS will NOT respond unless DNS is SPOT ON!
the ‘Fixing all the configs’ section should be the most help, probably. (though they may have different locations in ARCH)