Factory method and my mock object

[terminalXXX]

I have a class Customer I create a CustomerFactory for it but I would also like to include a Customer_Mock. So I think my factory will create a customer_mock instead of a real customer. Here is what I have done. But I am kept reminded of link error *.ctor as unresolved token and unresolved external symbol*. I am wrong about something I don't have an idea how to fix it myself. Thank you

using namespace System;

ref class Customer
{
    int age;
    String^ Name;
public:
    Customer();
    Customer(int a, String^ n)
    {
        Name=n;age=a;
    }
    virtual void Func()
    {
        Console::WriteLine(L"Customer Func");
    }
};

ref class Customer_Mock:Customer
{
    int age;
    String^ Name;
public:
    Customer_Mock( int age,String^name){this->age=age;this->Name=name;}
    virtual void Func() override
    {
        Console::WriteLine(L"Mock is called");
    }
};

ref class CustomerFactory
{    
    CustomerFactory(){Console::WriteLine(L"Customer Factory Constructor");}

public:    
    static Customer_Mock^ CreateCustomer(int age,String^name )
    {
        return gcnew Customer_Mock(age,name);
    }    
};


int main(array<System::String ^> ^args)
{
    Console::WriteLine(L"Hello World");
    Customer^c=CustomerFactory::CreateCustomer(10,L"simpson");
    c->Func();
    return 0;
}