Cronjob ignored in /etc/crontab?

Hi everyone,

I am struggling now with a task where I cannot find out why it simply does not work...

so this would be an automated backup script from an SG-210 Appliance Firmware: 9.700-5

so far, the share is reachable, the script creates a backup file via backup.plx and places it in a folder. then when it is ready it copies to the share via SSH key authentication. 

the script is executable (chmod -x %FILENAME%) and if I run the script like ./%FILENAME% it does it just fine.

Now I understand that the /etc/crontab file gets automatically overwritten by the webadmin like every 5minutes-ish except for the /etc/crontab-static. I add the script as a test like this:

vpn:/etc # cat crontab-static
SHELL=/bin/sh
PATH=/usr/bin:/usr/sbin:/sbin:/bin
MAILTO=""
15 * * * * root /etc/%SCRIPT%

this gets inserted in the crontab just fine... but simply, the file will not be executed. 

Manually executing, it is just fine. 

Any ideas on how to proceed troubleshooting?

Thanks in advance!