According to the codex what you have should be working. The only reason I can think that it isn’t is that if $post_object does not hold a post object in the way that WP is expecting.
If the page is broken, as in nothing is being displayed, then there is some kind of fatal error happening. You could put the following into your config.php file and see if you can see what the error is.
define( 'WP_DEBUG', true );
define( 'WP_DEBUG_DISPLAY', true );
