Page 2 sends me to Index.php

I am using page navi on two different queries. The first one works fine, but the second one sends me back to index.php when I try to navigate through the pages.

Thoughts ?

<?php
$this_cat_id = get_query_var(‘cat’);

$my_query = new WP_Query( array( ‘tag_id’ => $letter, ‘posts_per_page’ => 6, ‘cat’ => $this_cat_id, ‘paged’ => get_query_var(‘page’)) );

if (have_posts()) :while ( $my_query->have_posts() ) : $my_query->the_post(); ?>

<div id=”single”>
“><?php the_post_thumbnail(‘results_thumb’); ?>
<h2>“><?php the_title();?></h2>

<li class=”sport”><?php the_field(‘sport’); ?>
<?php echo “|”; ?><li class=”year”> <?php the_field(‘year’); ?><?php echo “|”; ?><li class=”category”> <?php the_field(‘category’); ?>

</div>
<?php endwhile; else: ?>

<?php endif; ?>

</div>
<?php wp_pagenavi( array( ‘query’ => $my_query ) );
wp_reset_postdata();
?>

https://www.ads-software.com/extend/plugins/wp-pagenavi/