cron job permission denied

Hi,

I scheduled a cron job, executed as root and command is /etc/webmin/backup/scripts/justatest

After the job run, I get an email telling me:
/bin/sh: /etc/webmin/backup/scripts/justatest: Permission denied

When I run the script manually it works.
This is the script:
#!/bin/sh
touch /etc/webmin/backup/test.txt
exit 0

owner/group of justatest is root, permission 755

Any ideas why I get permission denied?

Thanks,
Sebastian

chmod +x justatest ?