The same to me. Do a search, select from Jan 1 to Dec 1, then it can display the total earnings. Maybe there is something wrong with their server.
Give them some time, they are new ... and I believe as they have crossed the 30,000 publisher mark they need to fine tune their algo.
Trust me, this is happening to me and lots of people who own blogs. http://www.kedoa.com/blog/web/widgetbucks-and-feedburner-both-playing-up-today/