HTML output dont break page

I have a problem with HTML output
problem in line 5 first code (i must write an empty string WriteHTML(”) )
problem in body file line 3 (AddPage doesn’t work)

   self::init($param);
   ob_start();
   include $path . '/index.pdf.php';
   $output = ob_get_clean();
   self::$mpdf->WriteHTML(''); // this line must be exist Otherwise doesn't work
   self::$mpdf->WriteHTML($output);
   return self::$mpdf->Output($param['fileName'] . '.pdf', self::$dest);

and the index file :

<?php
include __DIR__ . '/header.pdf.php';
include $path . '/' . $body . '.pdf.php';
include $path . '/footer.pdf.php';

the body file :

<?php
echo 'A';
PDFHTML::addPageBreak(); //the only way to do a page break
self::$mpdf->AddPage(); //This line doesn't work
echo 'B';

i try to resolve the bug in my code source