It seems that you are also in the same boat , yes debit cards of any bank does not work anymore , i contacted my bank Standard Chartered and they told me that to make the online banking and the information of the their clients more secure they have limited the potential of the debit card use , All the online merchants do a test transaction before charging the card for the actual amount for $1 and then refunds it , now the Pakistani banks are only allowing one transaction which is the test transaction of $1 but when then merchants asks for the actual amount our banks declines the request , that is why we see error messages as (your card has been declined) (CVV2 security code does not match) . It took great effort to get this information out from my bank , these banks all know the answer but i do not know for some reason they are very hesitant to share this info.
A credit card does not have this problem .
Hope i have explained myself .