Why I cant Run Gii

Hi,


<?php

 Yii::setPathOfAlias('bootstrap', dirname(__FILE__).'/../extensions/bootstrap');

 return array(

    'theme'=>'bootstrap',

    'modules'=>array(

        'gii'=>array(

            'generatorPaths'=>array(

                'bootstrap.gii',

            ),                      

        ),

    ),


'import'=>array(

		'application.models.*',

		'application.components.*',

	),


	'modules'=>array(

		// uncomment the following to enable the Gii tool

	

		'gii'=>array(

			'class'=>'system.gii.GiiModule',

			'password'=>'saravanan',

			// If removed, Gii defaults to localhost only. Edit carefully to taste.

			'ipFilters'=>array('127.0.0.1'),

		),

		

	),


	// application components

	'components'=>array(

    	'bootstrap'=>array( 'class'=>'bootstrap.components.Bootstrap'),

		'cache'  => array(

                'class'  => 'system.caching.CFileCache',

        ),

?>



What is Wrong in my coding to generate model and controller i got error object not found how to solve?

Please, paste the whole error message, and stack trace.