rrd graphs for devmon scripts

Hi all,

 
Has anyone had any luck setting up a graph for a devmon collected
status? We are using devmon with a temperature monitor in our comms room
but at the moment it show the exact message so:

 
Temperature Probe:
Jacarta - interseptor
 
Average temperature: 21.65c
 
  Temperature at probe 1: 22.80c
 Temperature at probe 2: 20.50c

 
(the message made via devmon) gets plotted as: 
 
Temperature at probe 1: 22.80c  : nan(cur) : nan(max) : nan(min) .....
Temperature at probe 2: 20.50c  : nan(cur) : nan(max) : nan(min) .....
 
And instead of using any of the values simply makes more entries i.e.
Temp at probe 1 increases to 22.90 it plots

 
Temperature at probe 1: 22.80c  : nan(cur) : nan(max) : nan(min) .....
Temperature at probe 2: 20.50c  : nan(cur) : nan(max) : nan(min) .....
Temperature at probe 1: 22.90c  : nan(cur) : nan(max) : nan(min) .....
 
I have read the custom graph stuff from the help menu but that mainly
seems aimed at scripts you make yourself and doesn't work when applied
to this.  Help :-)
 
Thanks,
Jason.