title: Remove lastname field from checkout page in magento 1.9
body: <p>Is there a way to remove lastname field from checkout page ?
  i follow this tutotrial <a href="http://www.douglasradburn.co.uk/how-to-make-last-name-optional-in-magento-1-9/#comment-28589" rel="nofollow">http://www.douglasradburn.co.uk/how-to-make-last-name-optional-in-magento-1-9/#comment-28589</a> , but in the end it still show an error: lastname must to be greater than one 
  Thanks </p>