title: editing an Excel 2007 document with PHPExcel
body: <p>I have en excel 2007 document with 10 sheets but when I try to edit it with PHPExcel all the contents of those sheets (except the first one and the input made with PHPExcel) are erased. </p>
  
  <p>Here is my code:</p>
  
  <pre><code>require 'PHPExcel.php';
  require 'PHPExcel/IOFactory.php';
  require 'PHPExcel/Writer/Excel2007.php';
  
  $fileType = 'Excel2007';
  $fileName = 'test.xlsx';
  
  $objReader = PHPExcel_IOFactory::createReader($fileType);
  $objPHPExcel = $objReader-&gt;load($fileName);
  
  $activeSheet = $objPHPExcel-&gt;setActiveSheetIndexbyName('ID');
  $activeSheet-&gt;setCellValue('A2', 'string test');
  
  $objWriter = new PHPExcel_Writer_Excel2007($objPHPExcel);
  $objWriter-&gt;save($fileName);
  </code></pre>