How to implement password strength like in gmail registration in YII php? -

i want create password strength meter.i following estrongpassword yii used estrongpassword extension. put extension in extension folder , wrote code below:

<div class="row"> <?php echo $form->labelex($model,'password'); ?> <?php  $this->widget('ext.estrongpassword.estrongpassword',     array('form'=>$form, 'model'=>$model, 'attribute'=>'password'));  ?> <?php echo $form->error($model,'password'); ?> 

when checked file thorughs me error written below:

alias "ext.estrongpassword.estrongpassword" invalid. make sure points existing php file , file readable.  

i wondering how configure it,please me. in advance.

the code correct , shouldn't cause problems. here few things can try:

• make sure you've installed extension correctly
• check spelling in file names , class name correct. linux case sensitive.
• check extension folder protected/extensions , make sure directory estrongpassword (case sensitive) exists
• make sure path correct (ext in script refers protected/extensions path)

the file should at:

protected/extensions/estrongpassword/estrongpassword.php 

hope helps!