title: PHPExcel file not in the proper Microsoft Excel 2003 XLS format
body: <p>I'm generating a Excell 2003 using PHPExcel 1.8 with this code:</p>
  
  <pre><code>$objWriter = PHPExcel_IOFactory::createWriter($objPHPExcel, 'Excel5');
  $objWriter-&gt;save('toUploadFtp.xls');
  </code></pre>
  
  <p>The file seems ok, and I can read it using MS Office and LibreOffice.</p>
  
  <p>But I have to upload the file to a system that says the format has to be Excell 2003, and he prompts next error: </p>
  
  <blockquote>
    <p>Oops! Your file is not in the proper Microsoft Excel 2003 XLS format.</p>
  </blockquote>
  
  <p>If I open the file with LibreOffice and save it again, then I can upload the file correctly to the system.</p>
  
  <p>Any idea?</p>
  
  <p>Thanks,</p>