How to generate the root of the current page?

Thanks,

I found this function that makes the work ;

function get_breadcrumbs()
{
	global $wp_query;

	if ( !is_home() ){

		// Start the UL
		echo '<ul class="breadcrumbs">';
		// Add the Home link
		echo '<li><a href="'. get_settings('home') .'">'. get_bloginfo('name') .'</a></li>';

		if ( is_category() )
		{
			$catTitle = single_cat_title( "", false );
			$cat = get_cat_ID( $catTitle );
			echo "<li> &raquo; ". get_category_parents( $cat, TRUE, " &raquo; " ) ."</li>";
		}
		elseif ( is_archive() && !is_category() )
		{
			echo "<li> &raquo; Archives</li>";
		}
		elseif ( is_search() ) {

			echo "<li> &raquo; Search Results</li>";
		}
		elseif ( is_404() )
		{
			echo "<li> &raquo; 404 Not Found</li>";
		}
		elseif ( is_single() )
		{
			$category = get_the_category();
			$category_id = get_cat_ID( $category[0]->cat_name );

			echo '<li> &raquo; '. get_category_parents( $category_id, TRUE, " &raquo;</li><li> " );
			echo the_title('','', FALSE) ."</li>";
		}
		elseif ( is_page() )
		{
			$post = $wp_query->get_queried_object();

			if ( $post->post_parent == 0 ){

				echo "<li> &raquo; ".the_title('','', FALSE)."</li>";

			} else {
				/* Kindly borrowed and adapted from Breadcrumb Titles For Pages plugin
				http://wordpress.org/extend/plugins/page-breadcrumbs-for-wptitle/ */
				$title = the_title('','', FALSE);
				$prefix = "</li><li> &raquo; ";

				$seplocation = ( $prefix === substr( $title, strlen( $prefix ) * -1 ) ) ? 'right' : 'left';

				$ancestors = array_reverse( $post->ancestors );
				$ancestors[] = $post->ID;

				$titles = array();
				foreach ( $ancestors as $ancestor ){
					if( $ancestor != end($ancestors) ){
						$titles[] = '<a href="'. get_permalink($ancestor) .'">'. strip_tags( apply_filters( 'single_post_title', get_the_title( $ancestor ) ) ) .'</a>';
					} else {
						$titles[] = strip_tags( apply_filters( 'single_post_title', get_the_title( $ancestor ) ) );
					}
				}

				$title = implode( $prefix, $titles );

				if ( $seplocation == 'right' )
					$title = $title . $prefix;
				else
					$title = $prefix . $title;

				echo $title;
			}
		}

		// End the UL
		echo "</ul>";
	}
}

And then you call the breadcrumbs with;

<?php get_breadcrumbs(); ?>

The function works really fine on the WordPress 2.8 version, but as on the second site I am working on, I’m limited on the version 2.5, and I am getting the following error;

Warning: array_reverse() [function.array-reverse]: The argument should be an array in /usr/share/wordpress/wp-content/themes/cim/functions.php on line 470

Line 470 sounds: $ancestors = array_reverse( $post->ancestors );

What is the problem?