netsafe

I just registered for HDFC's netsafe, for a virtual credit card linked to my debit card. I generated a netsafe card and the first purchase went pretty well. However after generating a new card and trying it again (and again (and again)) for another purchase, paypal gives this error: I tried...

can anyone tell me what is HDFC netsafe virtual card, is it free, can we use it as a credit card