Problem for using rsync with cron

[David Bourgais]

Hello

I wrote a script shell to make backups. First, I execute my script
"manually" ans there is no problem. In a second part, I wrote a crontab
to launch my script as there :
31 11 14 11 * /home/gldavid/Coding/Shell/Backup/keepme.sh
My problem is when the script is launched by cron, I have an error in my
log and my backup is not effective :
rsync: getaddrinfo:  873: Name or service not known
rsync error: error in socket IO (code 10) at clientserver.c(94)
Is there a solution to correct this ?

Thank you very much for answer.

Have a nice day.

David