samba - Apr 2005 - wbinfo and getent work, join success, but unable to access server

i'm trying to setup samba on my nt4 network.

i use ;
fedora core 3
samba 3.0.14a-1

i want my samba server to be a member server of my domain

my smb.conf and nsswitch.conf are configured correctly
winbind ping is ok

wbinfo -u and -g returns good data
getent passwd and getent group returns good data

but, if i try to connect "\\computername", i get
"the format of the specified computer name is invalid"

+

wbinfo -t returns ;
"checking the trust secret via RPC calls failed
error code was NT_STATUS_INVALID_COMPUTER_NAME
could not check secret"

but i joined domain by entering
"net rpc join -U administrator"

plus, i had created the computer name in "server manager" on PRIMARY
DOMAIN
CONTROLLER before trying the join

please help