Перевести на C#

using System;
using System.Reflection;
using System.Runtime.InteropServices;
using Microsoft.Office.Interop.Excel;
........
Application app;
app = new Application();
Workbook myBook;
myBook = app.Workbooks.Open("Книга1.xls"); //Открываем книгу
Worksheet mySheet;
mySheet = myBook.Sheets.Item("Лист1"); //выбираем лист
object myCell;
myCell = mySheet.Range("A1", "B1"); //диапазон теперь

Почему не идёт программа?

using System;
using System.Collections.Generic;
using System.Windows.Forms;
using System.Reflection;
using System.Runtime.InteropServices;
using Microsoft.Office.Interop.Excel;

namespace WindowsApplication1
{

class XL
{
public Application app;
public Workbook myBook;
public Worksheet mySheet;
public object myCeel;

}

[STAThread]
static void Main()
{
app = new Application();
myBook = app.Workbooks.Open("Книга1.xls");
mySheet = myBook.Sheets.Item("Лист1");
myCell = mySheet.Range("A1", "B1");
}
}
}