[Samba] Samba as BDC: unable to write on shared folders

[Roberto Spedale - Studio Progetto Ambiente]

I use Samba as a PDC (non-AD-style) on the server n°1.
I have successfully created a BDC  on the server n°2.
I followed the official guide SAMBA 
(https://www.samba.org/samba/docs/man/Samba-HOWTO-Collection/samba-bdc.html) 

On servers n°2 I have also transferred the users database from the 
server n° 1 
(https://www.cyberciti.biz/faq/howto-move-migrate-user-accounts-old-to-new-server/) 

When I turn off the PDC my clients connect properly to the BDC.
But I can not write in the shared folders!! Shared folders are the same 
and with the same permissions of the server 1 (I used rsync -ra to 
backup them). The permissions seem ok but I can not write. I get the 
error "to perform the operation the" permission is needed.
I've also changed the logon on the BDC.
What tests can I do to figure out where is the problem?
many thanks

-- 
Dott. Ing. Roberto Spedale
Studio Progetto Ambiente s.r.l.
Corso Rosselli 44
10128 Torino
Tel: 011-58.17.359 Fax: 011-58.17.837
Email: r.spedale at studioprogettoambiente.eu
Web: http:\\www.studioprogettoambiente.eu