C++, MFC with C++ Wrapper CLI and C#DLL

Question

Hello!
I have big problems. Why is not working. What am I doing wrong?

C++/MFC EXE App --- CPPWrapper_CLI.DLL ---- C#DLL

How do I have to include the DLL in the exe, reference? How does that work?

Where can the cause be found? Is there a complete example so that I can see how it should work?

Wrapper Header
// CSharpCalcWrapper.h

#pragma once  

#include "atlstr.h"  

#ifdef CALCWRAP_EXPORTS  
#define CALCWRAP_API __declspec(dllexport)  
#else  
#define CALCWRAP_API __declspec(dllimport)  
#endif  


extern "C" CALCWRAP_API int CallSetupDialog();  
extern "C" CALCWRAP_API CString CallGetOrder(CString orderId);  
extern "C" CALCWRAP_API int Calc_Add(int a, int b);  

Wrapper CPP

/ This is the main DLL file.  

#include "stdafx.h"  
#include "CSharpCalcWrapper.h"  
#include "atlstr.h" // ** for CString  

#include <string>  
#include <iostream>  
//#include "CSharpCalcWrapper.h"  
using namespace System;  
using namespace std;  

using namespace CSharpCalculate;  



CALCWRAP_API CString CallGetOrder(CString orderId )  
{  
    String^ orderIdMES = gcnew String(orderId);  
    System::String^ managed  = StaticCalc::GetOrder(orderIdMES);  
    //String^ resMES = gcnew String(res);  

    //System::String^ str = "Hello World";  
    //std::string result = msclr::interop::marshal_as<std::string>(str);  

    //System::String^ managed = "test";  
    //std::string unmanaged2 = msclr::interop::marshal_as<std::string>(managed);  

    char cStr[5096] = { 0 };  
    String^ clrString = managed;  
    if (clrString->Length < sizeof(cStr))  
        sprintf(cStr, "%s", clrString);  
    std::string stlString(cStr);  

    CString ret = cStr;  
    //return unmanaged2;  

    //std::string jjj = StaticCalc::GetOrder();  
    //return ;  
    return ret;  
}  



CALCWRAP_API int CallSetupDialog()  
{  
    return StaticCalc::CallSetupDialog();    
}  


CALCWRAP_API int Calc_Add(int a, int b)  
{  
    //Calc obj;  
    //return obj.Add(a, b);  
    return StaticCalc::Add(a, b);  // if static!  
}  

CPP, MFC EXE.
How do I have to include the DLL in the exe, reference? How does that work?
Picture:

C#DLL

 static public class StaticCalc  
    {  
....  
 static public int CallSetupDialog()  
        {  
            SetupDlg = new frmSetup();  
            SetupDlg.ShowDialog();  
            return 0;  
        }  


        static public string GetOrder(string orderID)  
        {  
            string res =  "[ORDER]|0932342|42424|1000|R5E";  
            return res;  
        }  

   static public int Add(int a, int b)  
        {  
             return a +b;  
         }  


extern "C" CALCWRAP_API int CallSetupDialog();  
extern "C" CALCWRAP_API CString CallGetOrder(CString orderId);  
extern "C" CALCWRAP_API int Calc_Add(int a, int b);  

extern "C" CALCWRAP_API OrderProduct    GetOrderProduct(string order, double price);  

// Is it possible?   
// To get a JSON object as return value an then I can fill a C++ class/object?