Question about CIFS sharing / Can't delete file or folders "sometimes"

Hi guys,

I have this setup :

FreeNAS 9.2.1.8
One volume, several dataset.

For sharing, I use CIFS and NFS.

I have a separate machine that allows SFTP connections, and so the SFTP users can access the FreeNAS NFS shares... I did this way so FreeNAS stays "unexposed" to the Internet (or you know, at least not directly)

Every dataset was created for a CIFS share.

All dataset have USER = root and GROUP = a groupe that has the same name as the share / dataset

All permissions are UNIX...

Question about CIFS sharing / Can't delete file or folders "sometimes"