Unable to retrieve ccui.Button from CCNode in cocos2d-JS

Extensions
#1

I am unable to setTitle Text for ccui.Buttona a widget, its showing cannot read property ‘setTitleText’ of undefined in Cocos2d-JS

Here’s the code

SolutionGrid.setEmptySolutionBox = function(selChild,rChar) {

selChild.active = true;
cc.log("get tag of empty solutionBpx" + selChild.getTag());
var textButtons = ((ccui.Button)(selChild.getChildByTag(5)));
//var textButtons = ccui.Button(selChild.getChildren()[0]);
if(textButtons===null){
    cc.log("get tag of empty solutionBpx NULL");
}
///cc.log("get tag of empty solutionBpx" + textButtons.getTag());
textButtons.setTitleText("a");

};
where selChild is node on which ccui.Button is added

Here how its added , I am getting the tag of that node but can not find the ccui.Button as its child

solBox.addChild(textButton,5,5); //solBox is CCNode and text button is ccui.Button