Com.apple.Server.Accounts error 2 - Local Network Group problem

Question

I am lost :-)
just to specify, this is not a production server, it is just a learning platform for me.
I did a format and start over my server configuration
in order
DNS
DHCP
Open Directory
Profile Manager
User and group
File Sharing
very basic config.
Somewhere during user and group something happen
I did create a new Local Network Group and 2 Local Network User, me and a Directory admin
but now, when I create a group, it seem I can only create local group
and I can't edit Local Network Group
Local Group -> no problem
I can edit Local Group. I can add member
or I can go to a member and add it to a Local Group even if the user is a Local Network User
it work
Local Network Group -> does not work
I can't edit Local Network Group, can't add member
if i go the same Local Network user I added to local group and try to add it to a Local Network group, I get this error
com.apple.Server.Accounts error 2
I dont know where I went wrong :-)
any idea
Thank you

Answer 1

I just reformat and restart the configuration :-(   but I might have the same problem again, so i hope to understand why it happened.
I had the problem on both the server and a client machine.
Part of the Local Network User and Groups were greyed out, so I could not edit them
My airport setting for DNS was set to my server, so the client automatically got the local ip of the server for DNS.
On the server, initially, the formatting DNS IP was so to my airport, then I changed it to the DNS of my Internet provider. 
but for the self ip 127.0.0.1 i did saw it there at the begining but maybe when did change later it might have been affected.
I did changed the System Preferences>Network setting to a fix IP even if my airport was set as the DHCP with a fix IP for the Mac Mini.
I remember not seeing a DNS in that page. I will check for that now that I am about to start again.
and also, I tried to change the DHCP to be from given from the Mac Mini (like I read in the book) but when I did a
ipconfig getpacket en0
it was still showing the airport as the DHCP server
I will not set it this time.
Thank you
I will come back later with some update
Thank you