iCall / Automatic Backup Script / How to delete old backup files within iCall script?

Hi all!

I am using an iCall script to automate the configuration backups of BIGIPs. The script runs fine, except for the command to delete the old backup file(s). The exec rm command does not work when trying to delete files. Removing directories works well, but i don´t want to introduce a seperate directory for the backup files. Does anybody know, why the files don´t get deleted with the command in the line below "delete backup files"?

rgds, Peter.

modify script f5.archiving {
app-service none
    definition {
        delete backup files
        exec rm -f /shared/tmp/f5backup*
        Set Current Date/Time for Filename
        set cdate [clock format [clock seconds] -format "%Y%m%d%H%M%S"]
        Pull hostname from config for Filename
        set host [tmsh::get_field_value [lindex [tmsh::get_config sys global-settings] 0] hostname]
        Create Temp Directory
        set tmpdir [exec mktemp -d /shared/tmp/f5backup.XXXXXXXXXX]
        Set Filename Root
        set fname "f5backup-$host-$cdate"
        Export UCS
        tmsh::save /sys ucs $tmpdir/$fname
        Create Backup
        exec tar cvzf /shared/tmp/$fname.tar.gz -C $tmpdir . 2> /dev/null
        Remove Temp Directory
        exec rm -rf $tmpdir
        SSH settings
        exec scp /shared/tmp/$fname.tar.gz backup_user@10.128.20.20:/network/backups/f5/
}
description none
events none
}