[Samba] Idmap config Samba 4 NT4-style domain

[basti]

Hello,

I have a server with an NT4-style domain an Samba 4.2.14+dfsg-0+deb8u5.
The samba uses an LDAP backend and all is fine so far.

Samba users start at uid 1005 (it's not good I know but it's historical)
Domain Users Group has UID 513.

Now my Problem:
The winbind log is full of

[2017/04/07 16:35:50.896450,  1]
../source3/winbindd/idmap.c:230(idmap_init_domain)
  idmap range not specified for domain *

How should I config the idmap backend?
idmap_ldap has no entry in the wiki.

The groups I use are from 512 (domain admins) up to 2100 (somegroup)
with some spaces.

Thanks a lot, have a nice weekend.
Best Regards,
Basti