mrtg error in FC3

[Marcos-Fedora Brazil]

ERROR: Mrtg will most likely not work properly when the environment
       variable LANG is set to UTF-8. Please run mrtg in an environment
       where this is not the case. Try the following command to start:

       env LANG=C /usr/bin/mrtg /var/www/html/mrtg/genipabu.acib.com.br.cfg


what is?

thanks

Marcos