about event handle

Good morning!
I make the following changes:
in main(...):add some code like
                           Func * wsf;

in bro.init:add a line as global wsf: event (msg: string); in login.bro: add a event as
                           event wsf (msg: string)
                                 print msg;
And when I invoke bro : ./bro -i eth0 login.bro , bro does not work , with the error information :
              lin1: internal error: internal variable wsf missing
              Aborted .
Did I get the right way of creating and using event handle?
Any help is welcome.
Have a nice day.