而我的代码是印发错误的，为什么？

///////////////// .h
#ifndef HI_H_INCLUDED
#define HI_H_INCLUDED
#include <iostream>
using namespace std;
class Worker
{
    string name;

public:
    Worker(string na):name(na){}
private:    
    void data()
    {
        cout<<"worker"<<endl;
    }

};
class Waiter:virtual public Worker
{

public:
    Waiter(string na1):Worker(na1){}


    void show()
    {
        ((Worker &)*this).data();   ///强制转化为基类，为什么还是不能调用私有函数data()
        data();
    }
private:
    void data()
    {
        cout<<"waiter"<<endl;
    }
};


#endif // HI_H_INCLUDED

////////////  .cpp
#include <iostream>
#include "hi.h"
#include<stdlib.h>

using namespace std;


int main()
{
    Worker a("lin");
    Waiter b("liu");

    b.show();
    system("pause");
}