how to call custom config section from com interop

[iprogram2008]

I have a huge complex app.config and one of the sections in the config is connection strings.
I have a dot net class that uses this app.config and a com interop is generated for this dot net class. I developed an unmanaged c++ app and it calls the com interop tlb. The problem I was getting was when I call from C++ the tlb I get an null reference exception at the following line in .NetClass:

                MessageBox.Show(System.Configuration.ConfigurationManager.ConnectionStrings["TestConnString"].ConnectionString);

If I run in c# alone it has no problem identifying the connection string.
Does any one has any idea?.
I dont want to put the connection in app settings(which is visible for com interop) because this would involve a significant change in the application. Added to this there are numerous tags I need to read and retrieve
Thanks for any suggestions in advance



DotNet Class:

using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;
 
namespace NetClass
{
    [Guid("E4F73391-D64D-401a-B0B5-7C4559043313")]
    public interface IForm
    {
        void LaunchTestForm();
    }
 
    [Guid("2DF7C2CE-1068-4ff0-A053-0F641070568C")]
    [ClassInterface(ClassInterfaceType.None)] 
    public class TestClass : IForm
    {
        public TestClass()
        {
        }
        public void LaunchTestForm()
        {
            try
            {
                MessageBox.Show(System.Configuration.ConfigurationManager.ConnectionStrings["TestConnString"].ConnectionString);
                Form1 frm = new Form1();
                frm.ShowDialog();
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.ToString());
            }
 
        }
    }
}
 

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <connectionStrings>
        <add name="TestConnString" connectionString="Data Source=someserver;Initial Catalog=somedb;User ID=someuserid;Password=somepassword"
          providerName="System.Data.SqlClient" />
    </connectionStrings>
</configuration>
 

C++ WIN32 CONSOLE Application:

CoInitialize(NULL);    
 
NetClass::IFormPtr ptr;    
HRESULT hRes = ptr.CreateInstance(NetClass::CLSID_TestClass);
 
if (hRes == S_OK)
{
ptr->LaunchTestForm();
}