Both dirs have this config (names change for each dir, obviously):

chown root:users /srv/samba/share
chmod -R 2775 /srv/samba/share

smb.conf :
             [SHARE]
                      comment = Shared Data
                      path = /srv/samba/share
                      browseable = yes
                      guest ok = yes
                      force group = users
                      writeable = yes
                      create mask = 0664
                      force directory mode = 0775