You just answered your own question.
If you’re modfiying the in-build CRONTAB files, YOU must specify the user.
Your example did not:
* * * * * echo “Cron Test $(date)” >> /DataVolume/crontest.txt
Here’s what it should look like:
MyBookLive:/etc# cat /etc/crontab
# /etc/crontab: system-wide crontab
# Unlike any other crontab you don't have to run the `crontab'
# command to install the new version when you edit this file
# and files in /etc/cron.d. These files also have username fields,
# that none of the other crontabs do.
SHELL=/bin/sh
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin
# m h dom mon dow user command
17 * * * * root cd / && run-parts --report /etc/cron.hourly
25 6 * * * root test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.daily )
47 6 * * 7 root test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.weekly )
52 6 1 * * root test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.monthly )
* * * * * root echo "Cron Test $(date)" >> /DataVolume/crontest.txt
#
MyBookLive:/etc# cat /DataVolume/crontest.txt
Cron Test Mon Feb 13 06:58:01 CST 2012
Cron Test Mon Feb 13 06:59:01 CST 2012
Cron Test Mon Feb 13 07:00:02 CST 2012
