Using JExcel for reading and writing

I'm making a simple algorithm, to read an excel sheet, insert some records and save the changed sheet.

To write my code, I took as a basis the writing example provided with the JExcel package, so I have a method that is responsible for reading the worksheet, applying the content, writing that content to the worksheet, and saving it.

    public void gerarPlanilhaPreenchida(String inputFile, String outputFile) throws IOException, RowsExceededException, WriteException{

    File inputTemplate = new File(inputFile);
    File outputTemplate = new File(outputFile);

    Workbook planilhaTemplate;
    WritableWorkbook planilhaResultado;

    try{

        planilhaTemplate = Workbook.getWorkbook(inputTemplate);
        planilhaResultado = Workbook.createWorkbook(outputTemplate, planilhaTemplate);

        aplicaConteudo(planilhaResultado);

        planilhaResultado.write();
        planilhaResultado.close();

    }
    catch(BiffException e){
        e.printStackTrace();
    }

Here is the code of the method responsible for producing the content to be written, I started by simple inserting new lines in the worksheet:

    private void aplicaConteudo(WritableWorkbook w) throws WriteException {

    WritableSheet excelSheet = w.getSheet("INSS");
    excelSheet.insertRow(11);

}

To test:

    public static void main(String[] args) throws RowsExceededException, WriteException, IOException {

    String inputFile = "<<HOME_FOLDER>>/entrada/PlanilhaTemplate.xls";
    String outputFile = "<HOME_FOLDER<>>/saida/PlanilhaTemplate2.xls";

    GenerateExcelLogic novaPlanilhaTeste = new GenerateExcelLogic();
        novaPlanilhaTeste.gerarPlanilhaPreenchida(inputFile, outputFile);
}

This is the error log when running main :

  

Warning: can not insert row within formula: Unrecognized token 61
  Warning: can not insert row within formula: Unrecognized token 60
  Warning: can not insert row within formula: Unrecognized token 60
  Warning: can not insert row within formula: Unrecognized token 60
  Warning: can not insert row within formula: Unrecognized token 60
  Warning: can not insert row within formula: Unrecognized token 60
  Warning: can not insert row within formula: Unrecognized token 60
  Exception in thread "main" java.lang.NullPointerException
    at jxl.biff.formula.TokenFormulaParser.getBytes (TokenFormulaParser.java:495)
    at jxl.biff.formula.FormulaParser.getBytes (FormulaParser.java:183)
    at   jxl.write.biff.ReadFormulaRecord.getData (ReadFormulaRecord.java:145)
    at jxl.biff.WritableRecordData.getBytes (WritableRecordData.java:71)
    at jxl.write.biff.File.write (File.java:147)     at jxl.write.biff.RowRecord.writeCells (RowRecord.java:342)
    at jxl.write.biff.SheetWriter.write (SheetWriter.java:480)
    at jxl.write.biff.WritableSheetImpl.write (WritableSheetImpl.java:1558)
    at jxl.write.biff.WritableWorkbookImpl.write (WritableWorkbookImpl.java:950)
    at br.com.madi.projeto.GenerateExcelLogic.gerarInstructor (GenerateExcelLogic.java:45)
    at

NOTE: My Excel worksheet works as a Template , you just need to enter the data. In this case, when in insertRow() I ask him to insert a line inside my Template , I get the error above, now when the line is outside the Template , I do not receive the error. But I can not be sure if the worksheet has been changed or not.