About quota warning

I have a wd sharespace  network storage device. I create 5 user and a folder to share it. I give the user 5 gb limitation. But the user can store more than 5 gb. Now how can I solve this proble. And I want to set warning message if the user are going to cross their limit. How can this possible. Please answer someone me.

What firmware version do you have on your drive? I would make sure that you have the latest firmware. What are the steps that you took and how did you set the quota on the drive? When you check the users usage, how do you know that they are going over the 5GB limit that you set?

i had  updated latest  firmware of 30th June 2010 and still quota issue exist. Please help me.