Is not working with multiple translation files

[ursuleacv]

This is what I have in config

'preload' => array('log', 'jsTrans'),

'components' => array(
    'jsTrans'=>array( 
         'class'=>'application.extensions.JsTrans.JsTrans', 
            'categories'=>array('frontend', 'backend'), // the categories to be made available 
            'languages'=>array('en', 'fr'), // the languages to be made available
        ), 

the dictionary files are created in assets folder.

I have this structure for messages

protected/

• messages/
  • en/
    • backend.php
    • frontend.php
  • fr/
    • backend.php
    • frontend.php

and is working fine in php, But when I try in JavaScript with JsTrans I can access only variables from frontend

Yii.t('frontend', 'TRANS_VARIABLE') - working fine
Yii.t('backend', 'TRANS_VARIABLE') - not working

even though TRANS_VARIABLE exists in both frontend and backend
Can you help me please.