问错误-：'QObject::QObject‘：无法访问类'QObject’中声明的私有成员

EN

Error : 'QObject::QObject' : cannot access private member declared in class 'QObject'   

class B : public QObject
{
        Q_OBJECT
        private:
            ...
        public:
            B(QObject* parent = 0);
            ...
}

B:B(QObject *parent)
{
//Empty Constructor
}

class A
{
private:
     B myClassB;
public :
     B ReturnClassB();
}

B A::ReturnClassB()
{
   return myClassB; //This is where the error occurs
}