Chase closest player script not working?

I am trying to make an enemy that will chase the closest player but for some reason it just doesn't work, the thing doesn't move and I had tested before making the script, the thing will move. Here is my script:

local hum = script.Parent.Humanoid


local distance = 20

while true do
	for i,v in pairs(game.Players:GetChildren()) do
		if v.Character then
			local pos = (script.Parent.HumanoidRootPart.Position - v.Character.HumanoidRootPart.Position).magnitude
			if pos <= distance then
				hum:MoveTo(v.Character.HumanoidRootPart.Position)
			end
		end	
	end
	wait(5)
end

Can someone help?