Plesk 8.3:Need Help to enable Hard Disk Quota

[直樹æ]

I am a linux beginner and new to this stuff.
My /etc/fstab file looks like bellow.
Which line would I change to enable user quota's?

[root@ns etc]# cat fstab
LABEL=/ / ext3 defaults 1 1
LABEL=/var /var ext3 defaults 1 2
LABEL=/boot /boot ext3 defaults 1 2
tmpfs /dev/shm tmpfs defaults 0 0
devpts /dev/pts devpts gid=5,mode=620 0 0
sysfs /sys sysfs defaults 0 0
proc /proc proc defaults 0 0
LABEL=SWAP-sda3 swap swap defaults 0 0

I have tried bellow:

[root@ns etc]# cat fstab
LABEL=/ / ext3 defaults,usrquota 1 1
LABEL=/var /var ext3 defaults 1 2
LABEL=/boot /boot ext3 defaults 1 2
tmpfs /dev/shm tmpfs defaults 0 0
devpts /dev/pts devpts gid=5,mode=620 0 0
sysfs /sys sysfs defaults 0 0
proc /proc proc defaults 0 0
LABEL=SWAP-sda3 swap swap defaults 0 0

and have done bellow:
# mount -o remount /
# quotaoff -av
# quotacheck -avum
# quotaon -av
But did not work.

I wrongly posted the same question on Plesk8.1 forum. But my Plesk is actually 8.3.