Hispanic candidates have suffered political disappointments because of low turnout from their own voters.If there was any doubt about the importance of the Hispanic vote this election year, President Obama laid it to rest with his recent, aggressive courtship of Latino voters. But this month also provided fresh warnings to the Obama campaign that Hispanic voters, despite their growing numbers, aren't all that interested in turning out to vote.The evidence can be drawn from the House primaries that took place in states with significant Hispanic populations over the last month, particularly California, New York, and Texas. In contests from Southern...