proftpd with virtual users and sticky bit
 

hello guys , i succeed after a lot of time to make work proftpd with virtual users .i work with ftpasswd and i define all virtual users member of a "virtual group" ,called 1200. attention this GID dont exist in /etc/group si virtual users dont exists in /etc/passwd .

everithing is good ,the users are chrooted , i succeed to mount some common folders in which all the users can write with the underneath commands.
mount --bind /home/ftpwork /home/user1/work
mount --bind /home/ftpwork /home/user2/work
.....
.....
mount --bind /home/ftpwork /home/usern/work

and i define rights like this
drwxrws--- 2 root 1200 48 2007-12-05 10:28 ftpwork ,
this is the common folder pointed with mount --bind linkek by the folders "work" which are exist in all user's home directories.
after i mount this folders ,i can view that the permission rights are changed from
drwxr-xr-x 2 1102 users 48 2007-11-22 18:11 work ,
to
drwxrws--- 2 root 1200 48 2007-12-05 10:28 work
The problem is that the sticky bit defined for the "virtual group" 1200 doesnt work right,because a virtual user can delete a file that are put by another virtual user. i want that only the user which are put the file can overwrite or delete this file, all other users can only read this file. why the sticky bit dont work right ??????????????
drwxrws--- 2 root 1200 48 2007-12-05 10:28 ftpwork , that " s " from group rights must be the sticky bit but it doesnt work good.

please helppppppppppppp