Editing Excel sheet Using JXL library in android

Question

I am using jxl library in my application to edit excel file stored in external storage of galaxy tab. But every time i try to write the excel it creates a copy of existing excel file.It is writing all the values properly but my problem is that it is not creating other sheets present in excel file which are based on values from first sheet & some formulas. So when i read that newly created copy of excel file it shows me empty sheets other than first sheet.

            'Workbook workbook = Workbook.getWorkbook(new File(file));
    WritableWorkbook copy = Workbook.createWorkbook(new File(output.xls), workbook);

    WritableSheet sheet0 = copy.getSheet(0);

    WritableCell cell1 = sheet0.getWritableCell(3,4);

      Number n = (Number) cell1; 
      n.setValue(Systemsize);

    copy.write(); 
    copy.close();

Thanks