title: PHPExcel modify existing .xlsx file with multiple worksheet
body: <pre><code>
  require_once '../Classes/PHPExcel/IOFactory.php';
  
  
  /** PHPExcel */require_once '../Classes/PHPExcel.php';
  
  $excel2 = PHPExcel_IOFactory::createReader('Excel2007');
  $excel2 = $excel2->load('dentkey.xlsx');
  $excel2->setLoadAllSheets();
  $excel2->setActiveSheetIndex(0);
  $excel2->getActiveSheet()->setCellValue('C6', '4')           
  
  ->setCellValue('C7', '5')         
  
    ->setCellValue('C8', '6')       
  
      ->setCellValue('C9', '7');
  $excel2->setActiveSheetIndex(1);
  $excel2->getActiveSheet()->setCellValue('A7', '4')
  
  ->setCellValue('C7', '5');
  
  
  $objWriter = PHPExcel_IOFactory::createWriter($excel2, 'Excel2007');
  $objWriter->save('dentkey1.xlsx');
  
  
  </code></pre>
  
  <p>here, i am able to load (.xlsx) file and i also able to modify (dentkey.xlsx).
  But After generating new .xlsx file (dentkey1.xlsx)..all worksheets data which was in (dentkey.xlsx) is not loading and also i cannot set value for 2nd worksheet.</p>
  
  <p>you can fine</p>
  
  <pre><code>$excel2-&gt;setActiveSheetIndex(1);
  $excel2-&gt;getActiveSheet()-&gt;setCellValue('A7', '4')
  
  -&gt;setCellValue('C7', '5');
  </code></pre>
  
  <p>is not setting value 5 to 'C7' column of generated (dentkey.xlsx) file</p>
  
  <p>please help me...</p>
  
  <p>thanks a lot in advance</p>