I made a gui that sells a shirt from my friends group in his game, but it doesn't actually work.
local id = 920808270
script.Parent.ImageButton.MouseButton1Click:connect(function()
game.MarketplaceService:PromptProductPurchase(script.Parent.Parent.Parent, id)
end)
more details: the script and the imagebutton are both in a screen gui in the startergui
