access control through Builtin\administrators

Hi, i have a problem with granting access to a directory on OneFS. The ISILON Builtin\Administrators have full access to the directory and one AD user is member of this group but does not get access. Any suggestions how to grant the user access to the directory without adding him directly?

isi auth groups members list --group=Administrators
Type Name
----------------------------
group ddd..local\domänen-admins
user ddd.local\user1
----------------------------

drwxrwx--- + 2 ddd.local\adm_ffff ddd.local\domänen-benutzer 0 Sep 19 11:10 .
OWNER: user:ddd.local\adm_ffff
GROUP: group:ddd.local\domänen-benutzer
CONTROL:dacl_auto_inherited
0: group:Administrators allow dir_gen_all,object_inherit,container_inherit

Access for domain-admins works but not for user1

Thank you!