I have purchased the previous post add-on for single page. But its not working.

This is the code i have added in my single.php but this seems to be not working.
if ( have_posts() ) :
while (have_posts() ) : the_post();
echo do_shortcode(‘[ajax_load_more previous_post=”true” previous_post_id=”‘.get_the_ID().'” repeater=”template_1″ post_type=”post, page” post_format=”standard” category__not_in=”1515,933″ posts_per_page=”1″ pause=”true” scroll=”false” images_loaded=”true” max_pages=”2″ button_label=”Previous Post”]’);

endwhile;
endif;

Can someone please help me fix the issue.

My testing site url : https://staging-app.yourdost.com/blog