read/write,write/write lock with smbclient fails

Hi,
We have smb client running on two of the linux boxes and smb server on another linux system. During a backup operation which uses smb, read of a file was allowed while write to the same file was going on.Also simultaneous writes to the same file were allowed.Following are the settings in the smb.conf file:
lock directory =/var/samba/lock
locking=yes
strict locking = no
oplocks=yes
level2 oplocks = no
kernel oplocks =yes
raw read= yes
raw write = yes
Could anyone please let me know that what can I do to disallow read while write is going on and also restrict simultaneous writes?

Please tell us more about your configuration. What version of samba are you using? What flavor and version of linux are you using? Are all systems using the same version of Samba and Linux?