logwatch configuration issue

In both /usr/share/logwatch/default.conf/logwatch.conf and in /etc/logwatch/conf/logwatch.conf I specify the logs to report as:

Service =
Service = cron
Service = kernel
Service = postfix
Service = sshd
Service = syslogd
Service = xntpd
Service = zz-disk_space
Service = zz-fortune
Service = zz-lm_sensors

However, when logwatch runs (from root's crontab) it reports only postfix, disk_space, and lm_sensors.

I can provide the entire configuration file if asked.

What might be keeping all the other services from being reported?

TIA,

Rich