title: CException in Yiistrap .Alias bootstrap.helpers.TbHtml" is invalid
body: <p>In my web application I need to implement yiistrap .But I am getting this error and unable to rectify.Alias "bootstrap.helpers.TbHtml" is invalid. Make sure it points to an existing directory or file.
  My config/main.php</p>
  
  <pre><code>    &lt;?php
  
  // uncomment the following to define a path alias
  // Yii::setPathOfAlias('local','path/to/local-folder');
  
  // This is the main Web application configuration. Any writable
  // CWebApplication properties can be configured here.
  return array(
      'basePath'=&gt;dirname(__FILE__).DIRECTORY_SEPARATOR.'..',
      'name'=&gt;'My Web Application',
  'aliases' =&gt; array(
          'bootstrap' =&gt; realpath(__DIR__ . '/protected/config/extensions/bootstrap'), // change this if necessary
      ),
      // preloading 'log' component
      'preload'=&gt;array('log'),
  
      // autoloading model and component classes
      'import'=&gt;array(
          'application.models.*',
          'application.components.*',
  'bootstrap.helpers.TbHtml',
      ),
  
      'modules'=&gt;array(
          // uncomment the following to enable the Gii tool
  
          'gii'=&gt;array(
              'class'=&gt;'system.gii.GiiModule',
              'password'=&gt;'xxxx',
              // If removed, Gii defaults to localhost only. Edit carefully to taste.
              'ipFilters'=&gt;array('127.0.0.1','::1'),
  'generatorPaths' =&gt; array('bootstrap.gii'),
          ),
  
      ),
  
      // application components
      'components'=&gt;array(
          'user'=&gt;array(
              // enable cookie-based authentication
              'allowAutoLogin'=&gt;true,
          ),
          // uncomment the following to enable URLs in path-format
  
              'urlManager'=&gt;array(
                  'urlFormat'=&gt;'path',
                   'showScriptName' =&gt; false,
                   'rules'=&gt;array(
                         '/'=&gt;'/view',
                              '//'=&gt;'/',
                           '/'=&gt;'/',
                               ),             
                                  ),
  
  
          /*
          'db'=&gt;array(
              'connectionString' =&gt; 'sqlite:'.dirname(__FILE__).'/../data/testdrive.db',
          ),
                   */
          // uncomment the following to use a MySQL database
  
          'db'=&gt;array(
              'connectionString' =&gt; 'mysql:host=localhost;dbname=electrical',
              'emulatePrepare' =&gt; true,
              'username' =&gt; 'root',
              'password' =&gt; 'xxxxx',
              'charset' =&gt; 'utf8',
          ),
  
          'errorHandler'=&gt;array(
              // use 'site/error' action to display errors
              'errorAction'=&gt;'site/error',
          ),
          'log'=&gt;array(
              'class'=&gt;'CLogRouter',
              'routes'=&gt;array(
                  array(
                      'class'=&gt;'CFileLogRoute',
                      'levels'=&gt;'error, warning',
                  ),
                  // uncomment the following to show log messages on web pages
                  /*
                  array(
                      'class'=&gt;'CWebLogRoute',
                  ),
                  */
              ),
          ),
  'bootstrap' =&gt; array(
              'class' =&gt; 'bootstrap.components.TbApi',   
          ),
      ),
  
  
      // application-level parameters that can be accessed
      // using Yii::app()-&gt;params['paramName']
      'params'=&gt;array(
          // this is used in contact page
          'adminEmail'=&gt;'webmaster@example.com',
      ),
  );
  </code></pre>
  
  <p>Any body kindly help me with this. I am unable to proceed.</p>