10.5.5 server, ACL deny delete

Hi,

we have a 10.5.5 server (fresh install no migration) and for different sharepoints we want to avoid for most of the users to delete files or folders. Only some should be able to delete. So I set the Permissions for the different sharepoints:

ACL:
groupname > Deny > Custom (checked only Write: Delete, Delete Subfolders and Files)

POSIX:
User: admin > r/w
Group: staff > r/w
Others: none

Permissions Inspector shows that everything is as I want:
The groupmember(s) are allowed to do everything but “Delete” and “Delete Subfolders and Files”

When I connect from a client (10.5.4) the groupmember can only read. But as I understand the user should be able to write new files, append data, write date, …

Tried:
– create folder (sharepoint on bootvolume and external scsi-raid)
– switched systemlanguage from german to english
– used different groups an users (local and LDAP)

Any hints?