Cron-script server_password_chnage

Hi!
The Cron-Script /usr/lib/univention-server/server_password_change sents the Error-Message:
Failed to change server password for cn=pdc,cn=dc,cn=computers,dc=intern,dc=domain,dc=de
I find the following Messages in the log-File /var/log/univention/server_password_change.log:
(…)
run-parts: executing /usr/lib/univention-server/server_password_change.d/univention-samba4 prechange
Permission denied.
run-parts: executing /usr/lib/univention-server/server_password_change.d/50univention-mail-server nochange
(…)
failed to change server password for cn=pdc,cn=dc,cn=computers,dc=intern,dc=domain,dc=de
ls -l shows the correct rights:
ls -l /usr/lib/univention-server/server_password_change.d/
-rwxr-xr-x 1 root root 2112 Jul 30 15:32 50univention-mail-server
-rwxr-xr-x 1 root root 1294 Sep 22 20:22 portal-server-password-rotate
-rw-r–r-- 1 root root 393 Sep 18 20:08 README.API
-rwxr-xr-x 1 root root 1531 Jul 12 12:17 univention-admin-diary
-rwxr-xr-x 1 root root 1637 Sep 3 09:18 univention-bind
-rwxr-xr-x 1 root root 1666 Mai 24 2018 univention-dhcp
-rwxr-xr-x 1 root root 1314 Jul 23 11:43 univention-libnss-ldap
-rwxr-xr-x 1 root root 1320 Jul 23 11:43 univention-nscd
-rwxr-xr-x 1 root root 1472 Okt 1 16:36 univention-s4-connector
-rwxr-xr-x 1 root root 2961 Aug 5 13:50 univention-samba4
root@pdc:~#

But I can manualy execute /usr/lib/univention-server/server_password_change.d/univention-samba4 prechange without errors …

… Any Hints or more helpfull informations? …

Best Regards!