Why can't I buy Lindens?

Hi,
I have been trying to buy some Lindens for several days, both through the web site and direct in game, but am unable to do so.
The Error message I get on the web page is -
We are unable to complete your request.
• The system encountered an error while processing your order, please try again.

and I do. Again again and again - don't you want my money?

Try re-entering your billing info.. I remember reading somewhere that might work..

Thanks - it worked!