Customize Zii Messages

I just have copy /framework/messages/fa_ir/zii.php to /protected/messages/fa_ir/zii.php and changed it to my needs. but the messages to be translates from /framework/messages/fa_ir/zii.php instead /protected/messages/fa_ir/zii.php. What’s the reason?

notice that with /protected/messages/fa_ir/yii.php is no problem.

I configured coreMessages in /config/main.php as following:




    	. . . . 

    	'coreMessages'=>array(

        	'basePath'=>null,

    	),

    	. . . .



and the problem solved.

But why before configuring coreMessages, /protected/messages/yii.php applied but /protected/messages/zii.php didn’t applied!!!??? is anyone have my answer?