[Xymon] postfix monitoring plugin from xymonton -- graphs not working

I am using this plugin:

https://wiki.xymonton.org/doku.php/monitors:postfix

It works well, except the graphing. I made the suggested edits to the xymon config. I assume that either I screwed something up or the docs are out of date.

What can I do to get the graphs working? If info is needed to pinpoint the problem, please let me know and I will send it.

Thanks, Shawn