title: Codeigniter custom validation problem
body: <p>I'm trying to validate a username (connected to the mysql) but my coustom validation (callback) won't work.</p>
  
  <p>Controller
  <a href="http://pastebin.com/RLitWDYf" rel="nofollow">http://pastebin.com/RLitWDYf</a></p>
  
  <p>Model
  <a href="http://pastebin.com/6xygLwW5" rel="nofollow">http://pastebin.com/6xygLwW5</a></p>
  
  <p>How come my callback won't give any errors when a username is already in use? </p>