[Action Script] How do I remove monsters without removing players?

[Cadyan]

Fixed
I am using Mystic Spirit version 0.2.5 (client 9.8)

function onUse(cid, item, fromPosition, itemEx, toPosition)
	area1a = {x=1577, y=1321, z=4}
	area1b = {x=1580, y=1324, z=4}
	local monsters1 = {}
	for x = area1a.x, area1b.x do
		for y = area1a.y, area1b.y do
			for z = area1a.z, area1b.z do
				if(isCreature(getTopCreature({x = x, y = y, z = z}).uid)) then
					table.insert(monsters1, getTopCreature({x = x, y = y, z = z}).uid)
				end
			end
		end
	end

	for i = 1, #monsters1 do
		doRemoveCreature(monsters1[i])
	end
end

Bleh, I tried changing it to "if isMonster" and it worked (even though I do not see the function on the server list). I'll leave up it here for other people.