The second function just doesn't make any sense.
addEvent("onZombieWasted",true)
addEventHandler("onZombieWasted",root,
function (killer)
setElementData(killer, "Zombie Kills", getElementData(killer, "Zombie Kills") + 1)
end)
addEventHandler('onPlayerJoin', root, function()
setElementData(source, 'Zombie Kills', 0)
end)
addEventHandler('onResourceStart', root, function()
for index, player in pairs(getElementsByType('player')) do
setElementData(player, 'Zombie Kills', 0)
end
end)
Try to not use Zombie Kills as the element data, use something like 'zo' and a friendly name.