 We told you recently about a government program created to lift the poorest disabled and elderly people out of poverty. But its rules are so out of date and so complex that people often get kicked off. Then sometimes they're surprised to find that they owe money back to the government, maybe tens of thousands of dollars, money that they don't have because they're some of the poorest people in America. Now, the head of the agency that runs that program responds. NPR investigative correspondent Joseph Shapiro reports.