Yii Captcha Extended

Hey I am using an extension of yii captcha-extended Yii extended Captcha .The problem is that its work fine on localhost but when i upload this to my live link captcha picture is broken . i have checked my Gd extension it is enabled .i think that it is problem of path so

code for path to extension in ccontroller

public function init(){

        // register class paths for extension captcha extended

        Yii::$classMap = array_merge( Yii::$classMap, array(

            'CaptchaExtendedAction' => Yii::getPathOfAlias('ext.captchaExtended').DIRECTORY_SEPARATOR.'CaptchaExtendedAction.php',

            'CaptchaExtendedValidator' => Yii::getPathOfAlias('ext.captchaExtended').DIRECTORY_SEPARATOR.'CaptchaExtendedValidator.php'



model and controller is edited as in the extension page written

I need some quick reply . Thanks in advance.