It is possible to merge two different PDF-files with the Zend-Framework?
I try the script below, but I get the error:

--------------------------------------------------------------------------------------------
Uncaught exception 'Zend_Pdf_Exception' with message 'Page is attached to one documen, but rendered in context of another
--------------------------------------------------------------------------------------------

<?php
require_once 'Zend/Pdf.php';

$pdf1 = Zend_Pdf::load("1.pdf");
$pdf2 = Zend_Pdf::load("2.pdf");

foreach ($pdf2->pages as $page){
$pdf1->pages[] = $page;
}

$pdf1->save('3.pdf');
?>



What am i doing wrong?

Thank you for help!