samba - Sep 2005 - authentication problems from AD to NT4 domain w/samba servers

We have serveral samba servers in an NT4 domain that has a one way trust
to a larger AD forest.  I have verified that I can use an account in the
AD forest to login to a host in the NT4 domain.  

However if we try to mount a samba share in the above NT4 domain using a
user account in AD the mount fails even with a usermap.txt file lining
up the usernames.  I have an eleven page logfile that appears to
indicate that the AD forest is just pointing users at the NT4 domain and
not actually authenticating the user.  Because the AD username doesn't
exist in the NT4 domain the whole thing just fails.

any suggestions?

thanks,

Jeremy