[Samba] Problem saving AutoCAD files

[Info Cambria]

Hi all,

on my organization I have, on CentOS 6.5 x86_64, Samba 4.1.4 compiled and 
installed from source tarball.
Samba acts as AD and fileserver.
The problem is when the users try to save AutoCAD files on a share where all 
domain users have R+W rights.
Autocad refuses to save a file formerly saved by another domain user.
The message is: "AutoCAD unable to save drawing as it is being accessed by 
another session". Obviously, this is false: there is no other session 
accessing the file.
By the way, other kind of file, like Word, Excel, PDF, etc. don't show this 
issue.

My smb.conf::

# Global parameters

[global]
        workgroup = MYORG
        realm = MYORG.LOCAL
        netbios name = FILESERVER
        server role = active directory domain controller
        dns forwarder = 8.8.8.8

[netlogon]
        path = /usr/local/samba/var/locks/sysvol/myorg.local/scripts
        read only = No

[sysvol]
        path = /usr/local/samba/var/locks/sysvol
        read only = No


# common share

[condivisa]
        # this is the share where I have problems with AutoCAD files
        path = /home/condivisione
        read only = no
        create mask = 0777
        directory mask = 0777
        force create mode = 0777
        force directory mode = 0777


# user share

[j.smith]
        path = /home/j.smith
        read only = no

[t.hill]
        path = /home/t.hill
        read only = no

[l.dicaprio]
        path = /home/l.dicaprio
        read only = no

Any ideas?
Thanks in advance and sorry for my english :-)


Giovanni