PDF file is not opening after generating bar codes .

I have written a code to generate bar codes and saved them to a pdf file . The code executes successfylly but the PDF file does not open saying giving an error whome picture I am uploading. Please see my code and Picture with the error.

 public void createPDF(String pdfFileName,String myString) throws FileNotFoundException{
        Document doc = new Document() ;
        PdfWriter docwriter = null;

        try{
            docwriter = PdfWriter.getInstance(doc, new FileOutputStream("C:\\Users\\hp430\\Desktop\\barcodes\\"+pdfFileName));
            doc.addAuthor("Saboor Siddique");
            doc.addCreationDate();
            doc.addProducer();
            doc.addCreator("SunSoftTechnologies");
            doc.addTitle("Barcode Test");
            doc.setPageSize(PageSize.LETTER);
            doc.open();

            PdfContentByte cb= docwriter.getDirectContent();

            Barcode128 code128 = new Barcode128();
            code128.setCode(myString.trim());
            code128.setCodeType(Barcode128.CODE128);
            code128.setBarHeight(5f);
            code128.setX(0.1f);

            Image code128Image = code128.createImageWithBarcode(cb, null, null);
            code128Image.setAbsolutePosition(10, 700);
            code128Image.scalePercent(125);
            doc.add(code128Image);

        }
        catch(DocumentException dex){
            System.out.println(dex);
        }
    }