Buying Item Script Doesn't Work? Currencry Error?

Hey There,

Im The_Saver31

So i make this simple LocalScript:

local player = game.Players.LocalPlayer
local currency = player:WaitForChild("leaderstats").Coin -- Currency Name here.
local item = script.Parent.Parent.Parent.Item
local shop = game.Workspace.Shop
local tool = game.ReplicatedStorage:WaitForChild("Tools")

script.Parent.MouseButton1Click:Connect(function()
    if currency.Value >= shop:FindFirstChild("Part"..item.Value).ItemPrice.Value then
        if player.Backpack:FindFirstChild(shop:FindFirstChild("Part"..item.Value).ItemName.Value) == nil then
            if shop:FindFirstChild("Part"..item.Value) then
                currency.Value = currency.Value - shop:FindFirstChild("Part"..item.Value).ItemPrice.Value
                script.Parent.Text = "Bought"
                script.Parent.BackgroundColor3 = Color3.new(0.7,0.7,0.7)
                script.Parent.Shadow.BackgroundColor3 = Color3.new(0.5,0.5,0.5)
                game.ReplicatedStorage.ShopBuy:FireServer(item.Value)
                wait()
                currency.Value = currency.Value
            end
        end
     end
end)

All Fine! Item cloned, my Coin changed, BUTTT

Here What I Mean:

1. I Buy Item Priced 100 and my Coin is 200

2. Item Cloned and my Coi changed to 100

3. I pick a Coin that will give me 10 Coin

4. My Coin back to Normal, from 100 to 200 again [+10 because i pick a Coin]

Information: -Script was a LocalScript.

Thank's for Reading!