Why is my pagination for custom post type not working?

Here is the code I’m using to display the pagination…

<?php

global $wp_query;

$big = 999999999; // need an unlikely integer

echo paginate_links( array(

'base' => str_replace( $big, '%#%', esc_url( get_pagenum_link( $big ) ) ),

'format' => '?paged=%#%',

'current' => max( 1, get_query_var('paged') ),

'total' => $wp_query->max_num_pages

) );

?>

But when you click next and got to /page/2/ it says “Page Not Found”

what am I doing wrong???

Thanks ??

Terry