Fatal error in home.php

Hello everyone, My Problem is this message at the bottom of my page. Fatal error: Call to undefined function adventurous_content_nav() in /kunden/1234/webseiten/user/wp-content/themes/adventurous-pro/home.php on line 34 I use this Theme for a multisite. My code is

<?php
/**
 * The Home template file.
 *
 * @package Catch Themes
 * @subpackage Adventurous
 * @since Adventurous 1.0
 */

get_header();

        global $post, $wp_query, $adventurous_options_settings;

        // Getting data from Theme Options
        $options = $adventurous_options_settings;
        $enable_post = $options[ 'enable_posts_home' ];

        // Front page displays in Reading Settings
        $page_on_front = get_option('page_on_front') ;
        $page_for_posts = get_option('page_for_posts');

        // Get Page ID outside Loop
        $page_id = $wp_query->get_queried_object_id();

        if ( empty ( $enable_post ) || ( !empty( $page_id ) && $page_id == $page_for_posts ) ) {
?>

    <div id="primary" class="content-area">
        <div id="content" class="site-content" role="main">

        <?php if ( have_posts() ) : ?>

            <?php adventurous_content_nav( 'nav-above' ); ?>

            <?php /* Start the Loop */ ?>
            <?php while ( have_posts() ) : the_post(); ?>

                <?php
                    /* Include the Post-Format-specific template for the content.
                     * If you want to overload this in a child theme then include a file
                     * called content-___.php (where ___ is the Post Format name) and that will be used instead.
                     */
                    get_template_part( 'content', get_post_format() );
                ?>

            <?php endwhile; ?>

            <?php adventurous_content_nav( 'nav-below' ); ?>

        <?php else : ?>

            <?php get_template_part( 'no-results', 'index' ); ?>

        <?php endif; ?>

        </div><!-- #content .site-content -->

    </div><!-- #primary .content-area -->

        <?php
        get_sidebar();
}
get_footer(); ?>

Thanks for help :-)