title: Cannot create instance of abstract class
body: <p>I am trying to compile the following code and i am getting the error:</p>
  
  <p>Cannot create instance of abstract class . Please help</p>
  
  <pre><code>m_objExcel = new Excel.Application();
  m_objBooks = (Excel.Workbooks)m_objExcel.Workbooks;
  m_objBook = (Excel._Workbook)(m_objBooks.Add(m_objOpt));
  m_objSheets = (Excel.Sheets)m_objBook.Worksheets;
  m_objSheet = (Excel._Worksheet)(m_objSheets.get_Item(1));
  
  // Create an array for the headers and add it to cells A1:C1.
  object[] objHeaders = {"Order ID", "Amount", "Tax"};
  m_objRange = m_objSheet.get_Range("A1", "C1");
  m_objRange.Value = objHeaders;
  m_objFont = m_objRange.Font;
  m_objFont.Bold=true;
  
  // Create an array with 3 columns and 100 rows and add it to
  // the worksheet starting at cell A2.
  object[,] objData = new Object[100,3];
  Random rdm = new Random((int)DateTime.Now.Ticks);
  double nOrderAmt, nTax;
  for(int r=0;r&lt;100;r++)
  {
      objData[r,0] = "ORD" + r.ToString("0000");
      nOrderAmt = rdm.Next(1000);
      objData[r,1] = nOrderAmt.ToString("c");
      nTax = nOrderAmt*0.07;
      objData[r,2] = nTax.ToString("c");
  }
  m_objRange = m_objSheet.get_Range("A2", m_objOpt);
  m_objRange = m_objRange.get_Resize(100,3);
  m_objRange.Value = objData;
  
  // Save the Workbook and quit Excel.
  m_objBook.SaveAs(m_strSampleFolder + "Book2.xls", m_objOpt, m_objOpt,
      m_objOpt, m_objOpt, m_objOpt, Excel.XlSaveAsAccessMode.xlNoChange,
      m_objOpt, m_objOpt, m_objOpt, m_objOpt);
  m_objBook.Close(false, m_objOpt, m_objOpt);
  m_objExcel.Quit();
  </code></pre>