How to use magnitude properly?

This script isn't working, could someone please tell me what I'm doing wrong?

game.Players.PlayerAdded:Connect(function(plr)
	plr.CharacterAdded:Connect(function(char)
		char.HumanoidRootPart:GetPropertyChangedSignal("Position"):Connect(function()
		if (script.Parent.Position - char.HumanoidRootPart.Position).magnitude < 5 then
			script.Parent:Destroy()
		end
		end)
	end)
end)

Thanks!