Error de función indefinida al buscar en mi web

Fatal error: Call to undefined function tubeace_thumb() in /home3/**mi-usuario**/public_html/wp-content/themes/flat_tube/search.php on line 19

<?php get_header(); ?>
<section class="content">
	<div class="wrapper">
    	<div class="main-content">
  
		<?php if(have_posts()) { ?>  
	<div class="panel">
		<div class="p-title"><h2 style="background-color: #1AB3EE;">Searching for <?php $allsearch = &new WP_Query("s=$s&showposts=-1"); $key = wp_specialchars($s, 1); $count = $allsearch->post_count; _e(''); _e('<strong class="terms_search">'); echo $key; _e('</strong>'); _e(' - About '); echo $count . ' '; _e('results'); wp_reset_query(); ?></h2></div> 
	<div class="blog-list style-2">
         <?php while (have_posts()) : the_post(); ?>
         
            <!--Video Block -->
		<div class="video" id="video_<?php the_ID(); ?>">
            <a href="<?php the_permalink() ?>" title="<?php the_title(); ?>" class="thumb">
                <span><?php if(get_post_meta( get_the_ID(),'duration',true)) { echo tubeace_duration(get_post_meta( get_the_ID(),'duration',true)); } ?>
					<?php if(function_exists('bawpvc_views_sc')) {  ?><i><?php echo do_shortcode('[post_views id="'.get_the_id().'""]'); ?></i><?php } ?>
                 </span>   
                <i class="fa fa-play-circle-o"></i>
                <?php echo tubeace_thumb('latest',$post->post_title) ?>
            	<h4><?php echo tube_get_limited_string($post->post_title,42); ?></h4>
			</a>
		</div> 
        <?php endwhile; ?>
        <div class="cl"></div>
        <!--Pagination-->              
             <div class="pagination">
                <?php if (function_exists("pagination")) {
                    pagination($additional_loop->max_num_pages);
                } ?>
			</div>
        <!--END Pagination-->         
            
        <?php } else { ?>
            <h2>Sorry, no videos matched your criteria</h2>
        <?php } ?>   
	</div>
	</div>
		</div>
	</div>
</section>
<?php get_footer(); ?>

<?php get_header(); ?>
<section class="content">
	<div class="wrapper">
    	<div class="main-content">
  
		<?php if(have_posts()) { ?>  
	<div class="panel">
		<div class="p-title"><h2 style="background-color: #1AB3EE;">Searching for <?php $allsearch = &new WP_Query("s=$s&showposts=-1"); $key = wp_specialchars($s, 1); $count = $allsearch->post_count; _e(''); _e('<strong class="terms_search">'); echo $key; _e('</strong>'); _e(' - About '); echo $count . ' '; _e('results'); wp_reset_query(); ?></h2></div> 
	<div class="blog-list style-2">
         <?php while (have_posts()) : the_post(); ?>
         
            <!--Video Block -->
		<div class="video" id="video_<?php the_ID(); ?>">
            <a href="<?php the_permalink() ?>" title="<?php the_title(); ?>" class="thumb">
                <span><?php if(get_post_meta( get_the_ID(),'duration',true)) { echo tubeace_duration(get_post_meta( get_the_ID(),'duration',true)); } ?>
					<?php if(function_exists('bawpvc_views_sc')) {  ?><i><?php echo do_shortcode('[post_views id="'.get_the_id().'""]'); ?></i><?php } ?>
                 </span>   
                <i class="fa fa-play-circle-o"></i>
                <?php echo tubeace_thumb('latest',$post->post_title) ?>
            	<h4><?php echo tube_get_limited_string($post->post_title,42); ?></h4>
			</a>
		</div> 
        <?php endwhile; ?>
        <div class="cl"></div>
        <!--Pagination-->              
             <div class="pagination">
                <?php if (function_exists("pagination")) {
                    pagination($additional_loop->max_num_pages);
                } ?>
			</div>
        <!--END Pagination-->         
            
        <?php } else { ?>
            <h2>Sorry, no videos matched your criteria</h2>
        <?php } ?>   
	</div>
	</div>
		</div>
	</div>
</section>
<?php get_footer(); ?>

 <?php
/**
* The template for displaying Search Results pages.
*
*/ 
get_header(); ?>
	<div id="content">
		<?php if ( have_posts() ) :
			/* Start the Loop */ ?>
			<h1 class="larger_title">
				<?php printf( __( 'Search Results for: %s', 'reddish' ), '<span>' . get_search_query() . '</span>' ); ?>
			</h1>
			<?php while ( have_posts() ) : the_post();
				get_template_part( 'content', get_post_format() );
			endwhile;
			reddish_numeric_posts_nav(); /* post navigation */
		else :/* have post */
			get_template_part( 'no-results', 'search' );
		endif; ?><!--have_posts()-->
	</div><!--content-->
<?php get_sidebar();
get_footer();

<script>
  (function() {
    var cx = '003139723203244202343:e8mubil6vsg';
    var gcse = document.createElement('script');
    gcse.type = 'text/javascript';
    gcse.async = true;
    gcse.src = (document.location.protocol == 'https:' ? 'https:' : 'http:') +
        '//www.google.com/cse/cse.js?cx=' + cx;
    var s = document.getElementsByTagName('script')[0];
    s.parentNode.insertBefore(gcse, s);
  })();
</script>
<gcse:search></gcse:search>