Please take into consideration that payment providers sometimes don't accept payments or credit cards coming from a certain country.
If you are located in one of the following countries, you can make a payment using PayPal only:
Bulgaria
Belarus
Cote d'Ivoire
Indonesia
Lithuania
Macedonia
Pakistan
Romania
Ukraine
You can only use Paypal to purchase World Credits.
Payment providers don't accept credit cards or payments coming from the following countries:
Egypt
Lebanon
Morocco
Nigeria
Palestine
In this case, you could eventually ask a family member or a friend located in another country to pay for you.
If you are using an anonymous Proxy your payment will be rejected.