Gift Voucher problem

[Papaya]

Hi,

I bought the module and installed in my PrestaShop. But I encountered some problems.

I can not see the preview, fig.1.

And every time I make a purchase I get this window, with a zero. fig.2
But I have not bought the voucher! Why is going to appear this window every time I conclude an order?

Where did I go wrong?

Is there anyone who can help me?+

Thanks.