in cc.Layer keyBackClicked Not called

cocos2d-x JavaScript
#1

I call function this.setKeypadEnabled(true); in cc.layer, but keyBackClicked is not called。

#2

Here is my code:
MyClass.prototype.onDidLoadFromCCB

if( sys.os == "android" || sys.os == "Android") {
     this.rootNode.setKeypadEnabled(true);
}

this.rootNode.backClicked = function() {
     this.controller.backClicked();
     return true;
}

and

MyClass.prototype.backClicked = function(touches, event) {
     var mainScene = cc.BuilderReader.load("MainScene");
     cc.Director.getInstance().replaceScene(cc.TransitionFade.create(1.2, mainScene));
}
#3

I have the save problem. It will don’t work after click amazon ad and back game.