Sending data with CCNotificationCenter

cocos2d-x C++
#1

I have the following code in my application

    CCNotificationCenter::sharedNotificationCenter()->addObserver(
            this,
            callfuncO_selector(PingoScreen::printSomethingInCpp),
            "hello",
            NULL);

and

CCNotificationCenter::sharedNotificationCenter()->postNotification("hello",ccs(notificationData));

and

void PingoScreen::printSomethingInCpp(CCObject *pObject) {
    if(pObject){
        CCString * myData = (CCString*)pObject;
        CCLog("Its goton hererew 1212112---asasas-----------> %s",myData->getCString());
    }
}

But my notification function does not recieve any data ? What am i doing wrong ?

Kind Regards,
Muhammad Mateen