Why does this script not work?

I have this script for a zombie to find the closest person and chase him, but the findNearestTarget() function is not working. there is nothing in the output, please help!!

local player = script.Parent
local followingPath = false
torso = script.Parent.Torso
range = 500
target = nil

function findNearestTarget()
	for _, plr in pairs(game.Players:GetPlayers()) do
		if plr.Character ~= nil then
			tor = plr.Character.Torso
			if target ~= nil then
				if not target or (torso.Position-tor.Position).magnitude < (torso.Position-target.Torso.Position).magnitude then
						target = plr.Character
					break
				end
			end
		end
	end
end

while true do
	wait(.1)
	findNearestTarget()
	if target~=nil then
		script.Parent.tar.Value = Vector3.new(target.Torso.Position)
	end
end

while true do

	if not followingPath then
		followingPath = true
	path = game:GetService("PathfindingService"):ComputeRawPathAsync(player.Torso.Position, script.Parent.tar.Value, 500)
	points = path:GetPointCoordinates()
	
	game.Workspace.Points:ClearAllChildren()
	
	for p = 1, #points do
		local part = Instance.new("Part")
		part.Size = Vector3.new(1, 1, 1)
		part.Position = points[p]
		part.Anchored = true
		part.CanCollide = false
		part.Parent = game.Workspace.Points
	end
	
	for _, point in pairs(points) do
		script.Parent.Zombie:MoveTo(point)
		repeat
			distance = (point - player.Torso.Position).magnitude
			wait()
		until distance < 3
	end
	followingPath = false
	end
	wait(0.1)
end

Replace Line 12 with this:

if not target or (torso.Position-tor.Position).magnitude < (torso.Position-target.Torso.Position).magnitude then

i just made a free model for someone in the group to use its a alien that can chase and kill and be killed with guns / swords. u can change the looks to make it look like a zombie , i hope this helps.

http://www.roblox.com/alien-for-kid-item?id=174207024