Remove admin privilege for user account problem

I'm a new user to administrate the OS X 10.6.8 Server and meet many strange problems.

A mac client (OS X 10.7) cannot aftp://server with new user account. It will stay at the popup windows promtp without any error message. But it can login by user server's existing login account.

Then I re-create the same account name with admin group privilege. The mac client can login server's share and can view all shares too.

Then I remove the all admin group or admin privilege for this user account. No matther I reboot mac client. This user account can still view all server's shares. Actually, it could see one share folder "Artwork".

It is very strange that I tried it for several hours. Anyone can help what's wrong I did? Thanks much.

 

The problem is fixed now after checked that SACL membership failure.