Nagios hostgroup setup

I am trying to setup a Nagios Monitoring server (Nagios Core 3.2.3) on Ubuntu 10.10. I am having issues trying to setup hostgroups to separate everything, the items in the hostgoups keep duplicating throughout all of the hostgroups. I have tried creating a hostgroup.cfg file in the /usr/local/nagios/etc/objects/ directory and also tried specifing the hostgroup in the .cfg file for the individual host member. I am confused I’m sure I am just missing something, but I can’t figure out what it is. Any Ideas???

have youtried following the hostgroup part of the dcoumentation?
Remeber that if you add a cfg file you might need to add it in nagios.cfg

Luca