Using $node and $node->content within print_pdf.tpl.php

Why does the following code work in node.tpl.php, but not in print_pdf.node.tpl.php?

print_r($node->content['some_group']['#children']);

My node is a pretty complicated CCK-structure with fieldgroups, and the PDF-setup is also highly customised, so this is the easiest way I know to output a completely rendered fieldgroup, mixed with other fields and custom text.