The issue may be due to your client's location. Payments from the following regions are not supported:
Abkhazia, Afghanistan, Angola, Antarctica, Eland Islands, Barbados, Bangladesh, Burundi, Bolivia, the Democratic Republic of the Congo, Central African Republic, Congo, China, Colombia, Costa Rica, Cuba, Algeria, Ecuador, French Guiana, Guatemala, Guinea-Bissau, Honduras, Haiti, Iraq, Iran, Iceland, Kyrgyzstan, Cambodia, North Korea, Lebanon, Liberia, Libya, Morocco, Mali, Myanmar, Nicaragua, Nepal, South Ossetia, Panama, Peru, French Polynesia, Papua New Guinea, Pakistan, Palestine, Saudi Arabia, Sudan, Sierra Leone, Russian Federation, Somalia, South Sudan, Syria, Tunisia, Venezuela, Yemen, Zimbabwe.
Unfortunately, customers from these countries cannot make payments using this method.