monit howto

[Jamesk5]

I've tried to do the howto guide for the monit installation, but I'm getting a whole bunch of errors from cron delivered to my mail box.
Here's some of the more common ones:
Use of uninitialized value in concatenation (.) or string at /usr/share/perl5/Munin.pm line 784.

Cannot open /var/www/virtual/jameskirsop.mine.nu/monitoring/localdomain/localhost.localdomain-cpu.html at /usr/share/munin/munin-html line 488.

The 2nd error above is one that is repeated quite often.
I'm on Debian Etch, but I'm sure that it can't cause too many problems.

Anyone got any advice??
Thanks,
James