title: Excel file corrupted during write
body: <p>Whenever i try to manipulate an excel file,the corresponding excel file gets corrupted.
  Please give suggestion of how to tackle this thing. I have written the code in java. </p>
  
  <p>Here is the code:</p>
  
  <pre><code>Workbook workbook = Workbook.getWorkbook(new File("book.xls"));
  WritableWorkbook copy = Workbook.createWorkbook(newFile(""), workbook);
  WritableSheet sheet = copy.getSheet(0);
  WritableFont times16font = new WritableFont(WritableFont.TIMES, 20, WritableFont.BOLD); WritableCellFormat times16format = new WritableCellFormat (times16font);
  Label label = new Label(3, 4, "Good", times16format);
  sheet.addCell(label);
  Label label1 = new Label(3, 5, "Good", times16format);
  heet.addCell(label);
  copy.write();
  copy.close(); 
  </code></pre>