samba - Jun 2003 - Can't join linux machine to linux pdc controlled domain.

Getting error message:

Error connecting to my_pdc
Unable to join domain my_domain

when I run 'smbpasswd -j my_domain -r my_pdc' from linux_box

my_pdc is the primary domain controller for my_domain.  I have three 
win2k machines that are all using the pdc for domain authentication.  
They all work fine (funny enough) and can access the domain.

I have added linux_box$ to /etc/passwd on my_pdc.  I have also added it 
to smbpasswd using the following command 'smbpasswd -a -m linux_box'

I have added/updated these lines to smb.conf on linux_box
encrypt passwords = Yes
security = domain
password server = *

 samba daemons are not running on linux_box but are running on my_pdc 
during the "join" attempts..

linux_box can ping my_pdc. It can resolve my_pdc's ip address using 
nmblookup and my_pdc's netbois name.  I can use smbclient from linux_box 
to log into my_pdc and list the shares available.

I am running tcpdump on my_pdc.  I see traffic from other machines that 
are working correctly.  I do not see any traffic from linux_box to 
my_pdc during the "join" attempts

my_pdc is running samba 2.2.7 on redhat 7.3 kernel 2.4.20-18.7

linux_box is running samba 2.2.5 on redhat 7.3 kernel 2.4.18-5

I have gone into smbpasswd on my_pdc and deleted linux_box$ entry, then 
readded it and immediately tried to join again, with the same results, 
which shouldn't matter as no traffic is getting to my_pdc during the 
"join" attempts.

I've read the samba.org documentation and troubleshooting guide.  Good 
info on joining windows machines, but nothing on joining linux machines.

Any direction would be greatly appreciated.