MOBERLY, Mo. (AP) — Job creation is atop the agenda for President Barack Obama and his Republican challengers, as well as many candidates for state office in 2012. But the experience of state governments shows that business incentives don't always produce the results promised.The number of state business incentive programs has doubled over the past decade, to about 2,000 nationwide. And about two-thirds of the states now provide tax breaks specifically based on new jobs created.There is no nationwide accounting for how many of those incentives succeed or fail. But in Ohio, for example, about half of the 2,000 projects approved for job-creation tax credits have been canceled or terminated before completion. In Missouri, the recent failure of one business enrolled in an incentive program resulted in federal and state investigations.