[IRCServices] nickserv REGISTER problem

[Stanly]

Hello guys,

I've just installed IRC Services 5.1.9 and successfully configured it
to work with my ircd-hybrid-7.2.3+plexus-3.0.0

From modules.conf:

    NickServName    "NickServ" "Nickname Server"
    NSEnableRegister

But when I try to register using the command
/nickserv register passwd mailbox at domain.com
I get the following at the logs:

[Dec 26 21:59:22 2008] (nickserv/main) user record for Chaiko not found

User Chaiko is set as ServicesRoot at OperServ.

What am I doing wrong?
Thanks for your suggestions.

-- 
Best regards,
Stanly