[Samba] [HELP] Samba with myob trouble

[Aldyth Maharsha]

Hi list, i'm have trouble with MYOB. I'm running samba at debian squeeze
and share myob file. If one user access file, it is ok but rouble when multi
user access file, myob suddenly terminate and having error like this : *Unable
to open lock file ; access privileges may be incorrect or disk may be full *
It is my smb.conf :

[global]
        log file = /var/log/samba/log.%m
        passwd chat = *Enter\snew\s*\spassword:* %n\n
*Retype\snew\s*\spassword:* %n\n *password\supdated\ssuccessfully* .
        obey pam restrictions = yes
        encrypt passwords = true
        passwd program = /usr/bin/passwd %u
        passdb backend = tdbsam
        dns proxy = no
        server string = %h server
        unix password sync = yes
        workgroup = HUTANKITA
        syslog = 0
        security = user
        panic action = /usr/share/samba/panic-action %d
        max log size = 1000
        directory mode = 660
        pam password change = yes

[hfs_acc]
        write list = kristina,mini,yudi.prasetyo,meilani.sutanto, at hfs_acc
        force directory mode = 770
        force group = hfs_acc
        sync always = yes
        share modes = no
        oplocks = no
        delete readonly = yes
        locking = no
        writeable = yes
        path = /opt/share/hfs_acc/files
        force create mode = 770
        revalidate = yes
        valid users = kristina,mini,yudi.prasetyo,meilani.sutanto, at hfs_acc
        create mode = 775
        directory mode = 775
        level2 oplocks = no

Any Idea?, thanks before

Best Regards,
Aldyth M