[Samba] realm does not exist error

[Yoho, Cindy]

Hi All, 

I am trying to get Freeradius 1.1.7 on RHEL5 to authenticate using
Active Directory.  I have installed samba 3.0.28 and ran net join -U
administrator, entered my password, and got this:

Using short domain name -- UMPH
Joined 'ITRADIUS' to realm 'UMPUBLISHING.ORG'

When I do wbinfo -u I get users listed with the short domain name:

UMPH\jdoe
UMPH\mjohonson
UMPH\ldaniel
UMPH\....
.
.
etc

If I put the following line in my /etc/raddb/users file,

cyoho at umpublishing.org Auth-Type :- ntlm_auth

AD authentication works for jdoe (or whatever user I put in users file)
using radtest, NTradping, modem dialup, and just plain ntlm_auth on the
command line.

However, if I comment that line out, everything (radtest, dialup,
NTradping, etc) fails with the following error in the debug output:

rlm_realm: Looking up realm "umpublishing.org" for User-Name =
"jdoe at umpublishing.org"

rlm_realm: No such realm "umpublishing.org"

I enter the username as 

jdoe at umpublishing.org 

when attempting to login.

I tried logging in using UMPH\jdoe, but that does not work either.  I'd
like to get it to work using the long realm, since our AD admin says
that is our realm and our domain.

Thanks in advance~
Cindy