Hi Shoujo
I had this problem last week, but after trying to buy from the website accessed through your dashboard several times and being unsucessful I suddenly suceeded ?. It has nothing to do with your bank. It is a linden thing. They have changed the method for buying lindens for residents outside of the US.
It seems the only way we can buy now is through this website/ Secondlife Cashier/ I use viewer 2 and the beta version and I really like what they are doing with beta. Good luck