Scripting: Triggering an event when settlement is captured

Hi,
I've tried to make an event when the settlement Milan is capture by Venice.
monitor_event I_SettlementOwner Milan = Venice
add_events
event counter venice_c_milan
end_add_events
terminate_monitor
end_monitor
(I've already tried to swap the last two lines)
Appearently it doesn't work. And I have got absolutely no idea of scripting, so could somebody tell me what is wrong with code and how it should be in order to work,
Thanks in advance