Strange. I don't get any error you speak of when taking the test. It just gets accepted. I'm singed in so try signing first and then take the test. Either way, its still annoying maybe the website is still a work in progress who knows. You can also contact the author with the email provided in the about page.
This is the part in the article that I can relate to the most when people try to correlate richness with intelligence:
“Intelligence is not a factor for explaining wealth,” he said. “Those with low intelligence should not believe they are handicapped, and those with high intelligence should not believe they have an advantage.”