title: SpreadsheetGear - Issue with copying sheets from one Workbook to another
body: <p>I would like to merge all sheets from several Workbooks and save them in one excel file. I am trying to copy all the sheets in one Workbook and then save the workbook to a file. The problem is - only the last sheet is saved in the file. Below is some sample code. </p>
  
  <pre><code>public static void ExportSheets(string documentFilePath, List&lt;IWorkbook&gt; workbooks)
          {
              if (workbooks.Count &gt; 1)
              {
                  var destinationSourceBook = workbooks[0];
                  for (int i = 1; i &lt; workbooks.Count; i++)
                  {
                      var sourceWorkBook = workbooks[i];
                      for (int j = 0; j &lt; sourceWorkBook.Sheets.Count; j++)
                      {
                          sourceWorkBook.Sheets[j].CopyAfter(destinationSourceBook.Sheets[destinationSourceBook.Sheets.Count - 1]);
                      }
                  }
                  destinationSourceBook.SaveAs(documentFilePath, FileFormat.OpenXMLWorkbook);
              }
              else if (workbooks.Count == 1)
              {
                  workbooks[0].SaveAs(documentFilePath, FileFormat.OpenXMLWorkbook);
              }
          }
  </code></pre>
  
  <p>While debugging, I could see that the sheets are getting added to the destinationSourceBook.Sheets collection, but only the last sheet is present in the saved excel file. What is the right way to do this?</p>
  
  <p>Thanks</p>