there is a 30 second delay before you can use it again.
if it still doesnt work,
either use the reset command (!resetkill) with a level 100 user
or manually unset the variable %killon

UPDATE:
fixed a few bugs and added showing the kill/attack and killed/attack ratio.
(note that this is only if the persons with the info have killed or have been killed at least once.)

Meli,
you got it right on the %kill2 ;)

might change the thing \'you notice it isnt $2\' to a random name ;)
though i wouldnt make it complete randm for now
(might add an option to make it random)

there is a kick in the snippet, look under %kill2 == 5 in sucessfull kill.

M4g: yes, you must place this in remote.

SRD: i dont really know what you get,
you mean it should only work for a certain channel?
to do so: change the top line to: on 1:text:!kill:#yourchannel: {

AHBA: ill add that now, some delay for the messages.

UPDATE:
now you cant kill yourself.

current version: (V 2.2)