[CentOS] weird cron problem

Hi,

I'm having some problems with a script in /etc/cron.daily. It's quite
simple:
------
#!/bin/sh
touch /mnt/Backup/foo

rsnapshot daily
-----

So the touch gets executed, but the rsnapshot not. If I run manually

> run-parts /etc/cron.daily/ 

everything's fine. Also when I run rsnapshot from roots crontab. So I
have no idea what's the issue here.

Any ideas / recommendations what to check?

Andreas