Negative values in service graphs for nagios plugin not showing

Hi

I have a Nagios Plugin, that gives the following output with negative values:

TEMP FRYSER_BAGDOER OK|fryser_bagdoer=-21.5;-16.0;-16.0;;;

I have tried to follow the advice from here Custom Service with Negative Value Not Graphing - #3 by fulafisken without any luck. I have also tried to delete the service and add it again - also no luck.

Any advice would be appreciated.