ขอสอบถามเกี่ยวกับ PHP + เครื่องพิมพ์ใบกำกับภาษี ครับ

<style type="text/css" media="print">
html { margin-top:0px; padding: 0px;   }
body { margin-top:0%; margin-left:0%; margin-right:0%; font-size:11px; }
</style>

<?php

var_dump(printer_list(PRINTER_ENUM_LOCAL)); //<- this works fine and displays available printers

$handle = printer_open("HP LaserJet"); //<- this is where the fatal error occurs

printer_start_doc($handle, "My Document");
printer_start_page($handle);
$lfont = printer_create_font("Arial", 115, 40, 700, false, false, false, 0);
printer_select_font($handle, $lfont);
printer_draw_text($handle, 'Print current User: '.$user.'', 150, 2150);
printer_delete_font($lfont);
printer_end_page($handle);
printer_end_doc($handle);
printer_close($handle);

?>