Works on Local, but not on Server?

I've got a simple script that when it is clicked it will prompt a product purchase. Here is a sample code for a R$10 purchase.

productId = 33054891


script.Parent.ClickDetector.MouseClick:connect(function(plr)
    game:GetService("MarketplaceService"):PromptProductPurchase(plr, productId)
end)

script.Parent.ClickDetector.MouseHoverEnter:connect(function()
    script.Parent.SurfaceGui.Ammount.TextTransparency = 0.5
    script.Parent.SurfaceGui.Sign.TextTransparency = 0.5
    script.Parent.Enter.TextLabel.Visible = true
end)

script.Parent.ClickDetector.MouseHoverLeave:connect(function()
    script.Parent.SurfaceGui.Ammount.TextTransparency = 0
    script.Parent.SurfaceGui.Sign.TextTransparency = 0
    script.Parent.Enter.TextLabel.Visible = false
end)

Thank you in advance.