Controller not found

I am trying to develop a Plugin, with overriden class. The problem seems to be simple, but I am missing something.

Is it correct to override class in Plugin.php?:

public function getClasses()
{
 return array('plugins\CommentActions\Controller' => array('CommentActionsController'));
}

CommentActionsController.php:

class CommentActionsController extends CommentController
{

I get:

Internal Error: Controller not found