Why does this Dev Product script not give value when purchased?

Hey, there!

Thank you for wasting your time out of your day and clicking onto this to maybe help me with this script.

What I'm trying to make is a Dev Product that will give the user (when purchased the product) some leaderstat "strength". My stats handler is located in ServerScriptService, and then there is a folder "plr" with all the intValues in it, such as Strength, etc.

The problem is though, that I cannot get the script below to work.

I also do have another script which connects this with a TextButton in order to prompt the purchase to the user. (Which works as it prompts the user, just doesn't give the user 5 Strength when the user purchases the Dev Product).

Would anyone know why it doesn't give the user 5 Strength in their stats when purchased the Dev Product?

Thank you so much for reading and I will appreciate any help anyone is willing to give!

Script:

local MarketplaceService = game:GetService("MarketplaceService")
local ds = game:GetService("DataStoreService"):GetDataStore("PurchaseHistory")

CASHID = 1135295617

MarketplaceService.ProcessReceipt = function(receiptInfo)
    local playerProductKey = "player_" .. receiptInfo.PlayerId .. "_product_" .. receiptInfo.ProductId
    local numberBought = ds:IncrementAsync(playerProductKey, 1)
    for i,v in pairs (game.Players:GetChildren()) do
        if v.userId == receiptInfo.PlayerId then
            if receiptInfo.ProductId == CASHID then


                lds = v:FindFirstChild("plr")
                if lds ~= nil then
                    cs = lds:FindFirstChild("Strength") 
                    if cs ~= nil then
                        cs.Value = cs.Value + 5
                    end
                end
            end
        end
    end
    return Enum.ProductPurchaseDecision.PurchaseGranted     
end