cron_daily.sh do not write backups in /var/backup they stay uncompressed in /tmp

Hello,

1) Thank you !
First thank you for this great software, I use it for many years. I always found my answers in those forum so I didn't post. But right now I'm facing a problem with a new ISPConfig installation and it seems I can't find the solution on my own.

2) My ISPConfig version and installation informations
My ISPConfig version is ISPConfig 3.0.5.4p2 . I want to update but I would like to resolve this problem first. The operating system is CentOS release 6.5.
I have two ISP Config servers working in primary/secondary mode. I have some websites on the primary servers and some websites on the secondary. My primary server handles everything as primary server (DNS, mails, and so on) except websites which i wanted to distribute over the two servers to split the load.

3) My problem
Each time the script cron_daily.sh is called by crontab, it's supposed to write backups in /var/backup/<websiteid> . It works on all my servers with no problem. But on this one, I just see files in /tmp which stays here and aren't put in /var/backup.
This can end up with error 500 on websites if /tmp is full after a few tries.

I can't figure out why these backups are staying uncompressed in /tmp and with a temporary name.

I tried to run the script manually but didn't see anything wrong in the console.

Any idea ?

Thanks for your help.