It is not a 2 part insert, it is an insert, then update operation.
if you do it as a 2 part insert, you end up with 2 separate records.
on the second page, you need to use an update behavior to update the record that was created on the first page.
when a redirect is not working, it means that there is a php error occurring. add the following code to line one of the page to turn error reporting on:
<?php
error_reporting(E_ALL);
ini_set('display_errors','on');
?>