**if points > Cost then...** returning "user ... attempt to compare number with userdata"?

I created a button with a local script in it Link: http://i.imgur.com/ogML7pR.png.

Here is the code:

--              BUY SYSTEM, CREATED BY ASWORMEDORIJAN111, FOR TEST.
--                          7.4.2018.  OR    4/7/2018                                       




-- VARIABLES


Enabled = script.Parent.Enabled
Cost = script.Parent.SwordCost.Value
ItemName = script.Parent.SwordName.Value
local player = game.Players.LocalPlayer
local character = player.Character
local backpack = player.Backpack
local points = player.leaderstats


-- CODING SECTION


if (Enabled == true) then -- This is code for 'Enabled' value.
    script.Disabled = false
else
    script.Disabled = true
end

local itemf = game.Lighting
local item = itemf:FindFirstChild(ItemName)

function onclick()
    if points > Cost then 
        item:Clone().Parent = backpack
        points = points - Cost
    end
end

script.Parent.MouseButton1Click:connect(onclick)

And the output is here: http://i.imgur.com/DsnG4PE.png.******** Idk where did I failed... Sorry for my bad English.