i18n not working in Yii user-defined components

I created a simple component in my Yii project and there is a text on it that needs to be translated using i18n feature of Yii

    class MySimpleComponent{

   	public static function WelcomeCurrentUser(){

   		$wuser = Yii::t("lstrings","Welcome back ");

   		$wuser .= Yii::app()->session['curuser']; 

   		return $wuser;



I invoke that small component function in one of my views.

    echo MySimpleComponent::WelcomeCurrentUser();

but as i change the language in one of my controllers using the following code

    Yii::app()->language = 'ja' //change language to japanese

the translation doesn’t work… I double check my i18n strings to ensure that messages are exact to each other and still doesn’t work.

this is my lstrings.php file

    return array("Hello"=>"こんにちは",

                 "Welcome back "=>"お帰りなさい",


Any ideas why the translation does not work? any solutions? thanks