KILL : Unauthorised Command (Already Register)

[Bubux Le Pinguoin <bubux_news@xxxxxxxx>]

Hi, i am a french student. For my exam i want to present the installation
and the configuration of a IRC server. I choose IRCD-2.10.3.pl1. (tar.gz
version)
My Os is Mandrake Linux 7.2 (full installation).

My server works but i have a serious problem :
When i type /KILL nick reason  (after passing IRCOP with my login and
crypter password), i see the message "Unauthorised Command (Already
Register).

I have searched and i think that the problem is in compiling (config.h). 
What can i do to access to this command.

Thank you a lot
Bruno