LANSMM

Thanks for your help.
I have basically reinstalled everything…

Thanks for the quick answer. I already use a child theme (read all support post when installed the theme).
I tried with the pagenavi plugin, but it doesn’t work.
I changed template-tags.php as told by the plugin authors, but it just change nothing. I still have “previous posts” with an arrow.
Any ideas?
My template-tags.php looks this way:
<?php if ( is_single() ) : // navigation links for single posts ?>

<?php previous_post_link( <?php wp_pagenavi(); ?> ); ?>
<?php next_post_link( <?php wp_pagenavi(); ?> ); ?>

<?php elseif ( $wp_query->max_num_pages > 1 && ( is_home() || is_archive() || is_search() ) ) : // navigation links for home, archive, and search pages ?>

<?php if ( get_next_posts_link() ) : ?>
<?php wp_pagenavi(); ?>
<?php endif; ?>

<?php if ( get_previous_posts_link() ) : ?>
<?php wp_pagenavi(); ?>
<?php endif; ?>

<?php endif; ?>