"Feature is turned off" when using DevProducts?

I've got a DevProduct script, and so far I assume it works fine, but when I activate it, it gives me "Feature is turned off" in the Server Console. How can I fix this?

-- setup local variables
local MarketplaceService = Game:GetService("MarketplaceService")
local ds = game:GetService("DataStoreService"):GetDataStore("PurchaseHistory")
local productId = 20679593 
local Gems = 10

script.Parent.MouseButton1Click:connect(function()
local DeveloperProducts = game:GetService("MarketplaceService"):GetDeveloperProductsAsync():GetCurrentPage()
for _, DevProductContainer in pairs(DeveloperProducts) do
    for Field, Value in pairs(DevProductContainer) do
        print(Field .. ": " .. Value)
    end
end
end)

-- define function that will be called when purchase finished
MarketplaceService.ProcessReceipt = function(receiptInfo) 

	-- find the player based on the PlayerId in receiptInfo
	for i, player in ipairs(game.Players:GetChildren()) do
		if player.userId == receiptInfo.PlayerId then
			
			
			-- check which product was purchased
			if receiptInfo.ProductId == productId then
				
				-- handle purchase. In this case we are adding gems
				player.leaderstats.Gems.Value = player.leaderstats.Gems.Value + Gems
				
			end
		end
	end	
	
	-- record the transaction in a Data Store
	local playerProductKey = "p_" .. receiptInfo.PlayerId .. "_p_" .. receiptInfo.PurchaseId
	ds:IncrementAsync(playerProductKey, 1)	
	
	-- tell ROBLOX that we have successfully handled the transaction
	return Enum.ProductPurchaseDecision.PurchaseGranted		
end

If you can make this more efficient, or shorter, please feel free to do so.

The script handling the purchase must be in workspace, where as the script handling what you see when you click a button is a local script in the button. You can read more about it here: http://wiki.roblox.com/index.php?title=Developer_product If you have any more questions, just say.