tcpdf以大写字母Ñ代字符重音发出特殊字符

Hi im using tcpdf im using this code to set the font:

if ($PDFPaperSize == 'A4'){
$pagelayout = array(279.4, 215.9);
$pdf = new TCPDF(PDF_PAGE_ORIENTATION, PDF_UNIT, $pagelayout, true, 'UTF-8', false);
$Heavy = TCPDF_FONTS::addTTFfont(ROOTDIR."/modules/addons/assets/fonts/$font_family-Heavy.ttf", 'TrueTypeUnicode', '', 32);

but when i print a text in spanish like AÑOS means YEARS but in capital letters shows like A??S en the .pdf file, but if i remove the uppercase code turns Años or Years, and in pdf prints perfectly ok Años without ?? so im confused, theres any fix to allow acent in uppercase letters?

pd: code attached

http://pastebin.com/QvW04Xqc

thank you.