Rsync problems when run as a cron job

[Gabriel M Dragffy]

Hi,
I have the entry for root's crontab:

$ sudo crontab -l | grep rsync
Password:
00 08,15,20,00 * * * /usr/bin/rsync -rlvt
--delete /home /media/LACIE/Backup


This is a single example from syslog:
Aug 30 08:00:02 worldventuresltd /USR/SBIN/CRON[14748]: (root) CMD
(/usr/bin/rsync -rlvt --delete /home /media/LACIE/Backup)

Which shows the command got executed. However I am now certain that it
doesn't work, the data isn't transferred as it should. If I copy the
command exacatly from crontab (/usr/bin/rsync -rlvt
--delete /home /media/LACIE/Backup) and paste it into a terminal it does
it's job properly and very well.

Why isn't it working properly under cron?

Gabe