Breadcrumbs PHP code makes broken pages

WP:WordPress 3.5
WPSEO:1.4.19
PHP: 5.2.17

I used to use the breadcrumb’s PHP in my theme’s page.php. The original code were tuned to not display in home page.

<?php if( !is_front_page() ) { /* this it not home */
if ( function_exists('yoast_breadcrumb') ) {yoast_breadcrumb('<div id="breadcrumbs">','</div>');
};
} ?>

Today my site started to not render the html below this code. I try to use the original code from the plugin’s page where I enabled the breadcumbs, but have the same problem.

http://wordpress.org/plugins/wordpress-seo/