Apache PDFBox PDPageContentStream showText and drawImage sometimes don't work or show upside down

Regards,
I have a function that put page numbers and logos at right top.
The code works fine in almost every pages.
But, in some pages, the page number and its logo don't show.
In another pages, the page number and its logo show upside down at the left bottom.

Any idea about causes?

Code bellow, thanks.

    private byte[] setPageNumbers(byte[] pdftmp, Integer initialPage, Integer finalPage) throws IOException {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
PDDocument document = PDDocument.load(pdftmp);
PDPage page;
String numberingFormat = "  {0}";
int offset_X = 45;
int offset_Y = 803;
int page_counter = 1;
Color color = new Color(0);
float[] components = new float[] {color.getRed() / 255f, color.getGreen() / 255f, color.getBlue() / 255f };
float x;
float y;
PDPageContentStream contentStream;
PDRectangle pageSize;
String text;
PDImageXObject pdImage;
for(int i = initialPage; i <= finalPage; i++) {
page = document.getPage(i);
pageSize = page.getMediaBox();
x = pageSize.getLowerLeftX();
y = pageSize.getLowerLeftY();
text = MessageFormat.format(numberingFormat,page_counter);
contentStream = new PDPageContentStream(document, page, PDPageContentStream.AppendMode.APPEND, true, true);
contentStream.setFont(PDType1Font.HELVETICA_BOLD, 11);
contentStream.setNonStrokingColor(new PDColor(components, PDDeviceRGB.INSTANCE));
contentStream.beginText();
contentStream.newLineAtOffset(x + pageSize.getWidth() - offset_X, y+offset_Y);
contentStream.showText(text);
contentStream.endText();
++page_counter;		
pdImage = PDImageXObject.createFromFile(PDChoice.class.getResource("/images/logo.png").getPath(),document);
contentStream.drawImage(pdImage, x + pageSize.getWidth() - offset_X - 7, y + offset_Y - 2);
contentStream.close();					
}
document.save(baos);
document.close();
return baos.toByteArray();
}

I solved this way...

...
int degree;
float tx;
float ty;
width = Math.round(pageSize.getWidth()*25.4/72); // pts to mm
height = Math.round(pageSize.getHeight()*25.4/72); // pts to mm
degree = page.getRotation();
// I want A4 portrait...
// It's landscape... change to portrait
if (degree == 90 || degree == 270 || width > height) {
page.setRotation(0);
}
// It is not A4... change to
if (width != 210.0 || height != 297.0) {
page.setMediaBox(PDRectangle.A4);
}
...
// Some pages are right, but with rotation. I may not rotate this pages, so
// I rotate the content
if (degree == 180) {
tx = (pageSize.getLowerLeftX() + pageSize.getUpperRightX()) / 2;
ty = (pageSize.getLowerLeftY() + pageSize.getUpperRightY()) / 2;
contentStream.transform(Matrix.getTranslateInstance(tx, ty));
contentStream.transform(Matrix.getRotateInstance(Math.toRadians(180), 0, 0));
contentStream.transform(Matrix.getTranslateInstance(-tx, -ty));
}
...