WP_pagenavi does not show second page and more

Hi there

I have WP-PageNavi Version 2.87 installed on my site https://www.alympus.nl

When I click on the searchpage goes to the URL https://www.alympus.nl/zoeken/ where I can search. When getting a first page of result everything works fine, but when I get tot the second page or further I’m getting an 404- not found page. I’d like to know how to resolve this, but am stuck…

This is the code

<div id="content">
	<?php $posts=query_posts($query_string . '&posts_per_page=3'); ?>
	<?php if ( have_posts() ) : ?>
    <h1 class="page-title"><?php _e( 'results for ', 'theme' ); ?><span><?php the_search_query(); ?></span></h1>
        <?php while ( have_posts() ) : the_post() ?>
        <div id="post-<?php the_ID(); ?>" <?php post_class(); ?>>
        <h2 class="entry-title"><a href="<?php the_permalink(); ?>" title="<?php printf( __('more...', 'theme'), the_title_attribute('echo=0') ); ?>" rel="bookmark"><?php the_title(); ?></a></h2>
        <?php if ( $post->post_type == 'post' ) { ?>

        <?php } ?>
        <div class="entry-summary">
        <?php the_excerpt( __( 'Lees meer... <span class="meta-nav">&raquo;</span>', 'theme' )  ); ?>
        </div>
        </div>

        <?php endwhile; ?>
    	<?php // navigatie ?>
        <?php global $wp_query; $total_pages = $wp_query->max_num_pages; if ( $total_pages > 1 ) { ?>
	   	<div class="page-link"><?php if(function_exists('wp_pagenavi')) { wp_pagenavi(); } ?></div> 

        <?php } ?>
        <?php // noresults ?>
        <?php else : ?>
        <div id="post-0" class="post no-results not-found">
        <h2 class="entry-title"><?php _e("<!--:en-->We Found Nothing<!--:-->"); ?></h2>

        <div class="entry-content">
        <p><?php _e("<!--:en-->Your search has failed. Please try again. <!--:-->"); ?></p>
        <?php get_search_form(); ?>
        </div>

	</div>
    <?php endif; ?>
</div>