$autoload['libraries'] does not work at CodeIgniter_2.0.3

[eluser]Julia Yan[/eluser]
$autoload['libraries'] does not works in CodeIgniter_2.0.3

application/libraries/MY_Model

$autoload['libraries'] = array('database','session','parser','model'); //works on 1.7.0

But at 2.0.3 got An Error Was Encountered

Unable to load the requested class: Model