I JUST can’t get it to work (file sharing through Open Directory)

Here's the specs: Mac OS X Server 10.5.5 Running Services: AFP, DNS, iCal, iChat, Open Directory, SMB, Web I believe my DNS is setup correctly; the server is acting as an Open Directory Master, and the domain name is smpl-xserve.private. Kerberos realm is SMPL-XSERVE.PRIVATE. I've even successfully added the server's IP address to a client's DNS Server field in the Network preference pane, and added smpl-xserve.private in the Directory Utility app (also on the client). But, even though I am sure I have the usernames and passwords correct, I simply cannot authenticate to the server. The guest access does work, which proves that the share is being hosted correctly, but I am tempted to ditch the Open Directory approach and just use local user accounts to authenticate (we are just a small business so it wouldn't be that bad... I am just trying to do things the right way). Any tips would be much appreciated!