gathering data in cacti

[dhull]

I am trying to configure cacti following the instructions in the October issue of Linux Magazine. So far here is what I have.

1. Installed rrd tool from ports
2. Put cacti in my web root
3. Configured cacti according to docs
4. I am using "*/5 * * * * wget -O - http://localhost:81/cacti/cmd.php > /dev/null 2>&1" in my crontab to run "cmd.php". Some how this goes out and updates the graphs in cacti.

THE PROBLEM
The graphs show up in cacti but there's no data. I think this has something to do with the way Linux and FreeBSD us "/proc". I'm not really sure.

All I know is that there is no data in my graphs. 

QUESTION
How do I configure cacti to get data into the graphs?