posts_nav_link not working

This page, https://www.evolveea.com/our-thoughts, functions as the blog for my company site by calling up posts that are in the category “thoughts”.
It displays the 25 most recent posts (I set the max blog posts to display at 25), and I would like nav links at the bottom of that list of posts to let readers navigate further back to the next 25 older posts. This code is in my template but nothing is showing up at all (furthermore, when I use Chrome’s inspector, I do not even see the html that I put around the php code–no div opening or closing is showing there):
<div class="blog-post-wrap"><div class="subtitle"><?php posts_nav_link( ' ', '<img src="https://www.evolveea.com/wp-content/themes/evolveEA/images/arrowback.png"> Previous', 'More Thoughts <img src="https://www.evolveea.com/wp-content/themes/evolveEA/images/arrowlist.png">' ); ?></div></div>

what could I be doing wrong here? I have tried moving the code in and out of the loop and to other parts of the page, and I read many posts about this function without finding anything that explains my problem. Can anyone help?