I don´t know how to make this plugin work

Hello!
Firts of all I’m sorry for my bad english.
I’m a Nagios Newbie and I want to install the plugin check_fortigate.pl, I already install perl and every time I tried to prove the command

check_fortigate.pl -H 192.168.200.254 -C public -T cluster
The server says: check_fortigate.pl: command not found

So I don’t know how to make it works.
Any help will be great!

Thanks!
Regards from México!