samba - Feb 2008 - Listing users from a group (net rap groupmember list)

Hello list!

I've been trying to list the users from a group of my samba server
(running on an OpenBSD 4.2 box) by using "net rap groupmember list
GROUPNAME -S PDC -U administrator%password -w DOMAIN", but I get
nothing in return.

By running the command with a -d for debug purposes, I get the messages above:

 /usr/ports/net/samba/w-samba-3.0.25b-cups/samba-3.0.25b/source/libsmb/clirap2.c:cli_NetGroupGetUsers(548)
  NetGroupGetUsers gave error 2220
/usr/ports/net/samba/w-samba-3.0.25b-cups/samba-3.0.25b/source/libsmb/clirap2.c:cli_NetGroupGetUsers(566)
  NetGroupGetUsers no data returned

The souce file (clirap2.c) tells me that error 2220 means "Group does
not exist". But I'm pretty sure that the group I'm looking for does
exist.

I'm lost here. Is "net rap groupmember list" broken? Or do I have
a
problem in my setup?

Thanks in advance!

Leonardo Rodrigues

PS. I'm not subscribed to the list, please CC me.