Как исправить ошибку error C2039 "не является членом класса"?

#include "stdafx.h"
#include "Employee.hpp"
#include <iostream>
using namespace System;
Employee::Employee(int initialAge)
{
    itsAge = initialAge;
}
 
Employee::~Employee()
{
}
 
int main()
{
    Employee Jon(26);
    std::cout<<"Jon is a man who is "<< Jon.GetAge()<<"years old.\n"<<std::endl;
    Jon.YearsofService(5);
    std::cout<<"Jon Years of Service = "<<Jon.YearsofService()<<"\n"<<std::endl;
    Jon.Salary(30000);
    std::cout<<"Jon salary = "<<Jon.Salary()<<"\n"<<std::endl;
    return 0;
}

#include <iostream>
class Employee
{
public:
    Employee (int initialAge);
    ~Employee();
    int GetAge() const {return itsAge;}
    void SetAge (int Age) {itsAge=Age;}
    int GetYearsofService() const {return itsYearsofService;}
    void SetYearsofService(int YearsofService) {itsYearsofService=YearsofService;}
    int GetSalary() const {return itsSalary;}
    void SetSalary(int Salary) {itsSalary=Salary;}
private:
    int itsAge;
    int itsYearsofService;
    int itsSalary;
};

Jon.SetYearsofService(5);
std::cout<<"Jon Years of Service = "<<Jon.GetYearsofService()<<"\n"<<std::endl;
Jon.SetSalary(30000);
std::cout<<"Jon salary = "<<Jon.GetSalary()<<"\n"<<std::endl;

Jon.SetYearsofService(5);
std::cout<<"Jon Years of Service = "<<Jon.GetYearsofService()<<"\n"<<std::endl;
Jon.SetSalary(30000);
std::cout<<"Jon salary = "<<Jon.GetSalary()<<"\n"<<std::endl;