[Samba] problem with group mapping

[mamue at lb-bbs1.emd.ni.schule.de]

Hi,
I use now samba3.0.1pre1 with ldapsam (OpenLDAP 2.1.23).
After I played with sambaGroupMapping I now get the error Message:
"Die angegebene Gruppe ist nicht vorhanden"
"The given group does not exist"
when I log in (administrator).
Admin's SID is: S-1-5-21-1091375802-1471697927-1951840895-500
Domain SID is: S-1-5-21-1091375802-1471697927-1951840895

The error occured after I created a administrators group in ldap with
(first free) gid 3019 and SID
S-1-5-21-1091375802-1471697927-1951840895-512
and added groupMapping to my "susers" (all samba users) with rid 513 and
created for testing a group guest with no memberUIDs and rid 514.
All groups had type 0 (zero).
I removed all those groups, but the error remains.
PDC and BDC have same Domain-SID.
What did I do wrong, or what ist the correct way to do this?
I especially don't know what to do with group "guest" - is this nobody or
nogroup in unix?
I read across the documentation but didn't find someting helpfull or did I
read across some important points?

Thanks in advance for any help,
Malte Müller