Erro Invasao

[20:10:59.975] [Error - GlobalEvent Interface]
[20:10:59.977] data/globalevents/scripts/invasao.lua:onThink
[20:10:59.979] Description:
[20:10:59.981] data/globalevents/scripts/invasao.lua:13: 'for' limit must be a number
[20:10:59.982] stack traceback:
[20:10:59.984]  data/globalevents/scripts/invasao.lua:13: in function <data/globalevents/scripts/invasao.lua:7>
[20:10:59.989] [Error - GlobalEvents::think] Couldn't execute event: invasion

local i = {
["20:10"] = {nome = "Sambi Evento", pos = {x=1001, y=888, z=7}, monster = {"bi"}},
["16:35"] = {nome = "Hachibi Evento", pos = {x=1004, y=917, z=7}, monster = {"ha"}},
["13:30"] = {nome = "Kyuubi Evento", pos = {x=1021, y=912, z=7}, monster = {"ki"}},
}
 
function onThink(interval, lastExecution)
hours = tostring(os.date("%X")):sub(1, 5)
tb = i[hours]
if tb then
doBroadcastMessage(hours .. " - " .. tb.nome .. " Acaba de Ser Iniciado.")
for _,x in pairs(tb.monster) do
for s = 1, tonumber(x:match("%d+")) do
doSummonCreature(x:match("%s(.+)"), tb.pos)
end
end
end
return true
end