Apologies, this is a re-occurring problem. I've found that if I scroll down on the page farther, creating 2 inches between the "Send" button and the bottom of the browser window, then it works. When the Send button is took close to the bottom of the page, it doesn't work but also doesn't give you an error message, which is frustrating.
If that doesn't work, sometimes a new browser, like Google Chrome works better, especially than Internet Explorer. http://www.google.com/chrome/intl/en/make/download.html?&brand=...