Hi, we are using Smart Payment Buttons to receive payments from our customers. The customer gets a link with url parameters including invoice number and amount. And so far it worked well. But suddenly the form doesn't work anymore if you don't change the prize by hand prior to using the buttons. If you just look at it and click them, they simply don't work anymore. Any ideas what to change? I tried to change the field type to text instead, but that doesn't help either.