in auth/auth_domain.c in the function domain_client_validate() user_info->client_domain is passed to rpccli_netlogon_sam_network_logon().
If that call fails, however, the domain value reported via the debugging output is user_info->domain. Changing 'user_info->domain' to 'user_info->client_domain' in the DEBUG line will help preserve the sanity of users attempting to figure out why things look right but arn't working.
This problem exists in older versions, but was found in 3.0.28a. (which isn't selectable in the Version menu scrollbox above.. which is a different bug, I suppose :) )