What the hell???

I was trying to pay for something with my credit card, I filled in the long number and the expiry date boxes, then I typed the three digits of the security code.
    Then the stoopidest, most useless bit of programing in the universe told me the number was incomplete or insufficient or something like that.
    Well, I just went to the top-right of the window and clicked on the X. Sometimes, you just have to move on.