WoWInterface - Extract id of a killed npc

Hello.

I'm trying to extract the NPC ID of a npc I just killed (when I'm in a group).

I have the next code:

Code:

myFrame:RegisterEvent("COMBAT_LOG_EVENT_UNFILTERED")

myFrame:SetScript("OnEvent", function(self, event, ...)

        if (event == "COMBAT_LOG_EVENT_UNFILTERED") then

                local timestamp, eventType, hideCaster, sourceGUID, sourceName, sourceFlags, sourceRaidFlags, destGUID, destName, destFlags, destRaidFlags = ...

                if (eventType == "PARTY_KILL" or eventType == "UNIT_DIED") then

                        local _, _, _, _, _, id = strsplit("-", destGUID)

                        print("ID found "..id)

                end

        end

end)

This works sometimes... a lot of times the event is not fired.

Do you know if there are some limitations with this events or if I'm doing something wrong?

Thanks