[Samba] net groupmap add/modify script fails

[Jeremy]

I am following the installation described in Chapter 3 of Samba By Example
(http://samba.org/samba/docs/man/Samba-Guide/secure.html) and at Step 5 i run
into the following problem:

I copied the example script to /etc/samba/initGrps.sh and customized the group
names, then

brandy:/etc/samba# chmod 755 initGrps.sh
brandy:/etc/samba# ./initGrps.sh

groupadd: group akkaras exists
groupadd: group aksteinhilber exists
groupadd: group akstark exists
Updated mapping entry for Domain Admins
Updated mapping entry for Domain Users
Updated mapping entry for Domain Guests
No rid or sid specified, choosing algorithmic mapping
adding entry for group AK Karas failed!
No rid or sid specified, choosing algorithmic mapping
adding entry for group AK Steinhilber failed!
No rid or sid specified, choosing algorithmic mapping
adding entry for group AK Stark failed!

Then after RTFMing I tried

brandy:/etc/samba# net groupmap list | sort
Account Operators (S-1-5-32-548) -> -1
Administrators (S-1-5-32-544) -> -1
AK Karas (S-1-5-21-1348455924-348699262-4184906134-3003) -> akkaras
AK Stark (S-1-5-21-1348455924-348699262-4184906134-3007) -> akstark
AK Steinhilber (S-1-5-21-1348455924-348699262-4184906134-3005) -> aksteinhilber
Backup Operators (S-1-5-32-551) -> -1
Domain Admins (S-1-5-21-1348455924-348699262-4184906134-512) -> root
Domain Admins (S-1-5-21-1972254233-2250998545-1379234658-512) -> -1
Domain Guests (S-1-5-21-1348455924-348699262-4184906134-514) -> nogroup
Domain Guests (S-1-5-21-1972254233-2250998545-1379234658-514) -> -1
Domain Users (S-1-5-21-1348455924-348699262-4184906134-513) -> -1
Domain Users (S-1-5-21-1972254233-2250998545-1379234658-513) -> users
Guests (S-1-5-32-546) -> -1
Power Users (S-1-5-32-547) -> -1
Print Operators (S-1-5-32-550) -> -1
Replicators (S-1-5-32-552) -> -1
System Operators (S-1-5-32-549) -> -1

So, it appears (atleast to me) that the mapping has worked, but what is failing
then?

Thanks in advance!!!