这个是买家的paypal有问题，被paypal风控挡住了，不是程序和卖家收款paypal的问题，详细参看下面的链接：
https://developer.paypal.com/docs/classic/express-checkout/ht_ec_fundingfailure10486/
A funding source may fail for these reasons:
The billing address associated with the financial instrument could not be confirmed.
The transaction exceeds the card limit.
The transaction was denied by the card issuer.