WordPress add_rewrite_rule working on Apache, not on IIS

I am having the following rewrite rule : add_action( ‘init’, ‘custom_rewrite_rules’ ); function custom_rewrite_rules() { add_rewrite_rule(‘formation(/([^/]+))?(/([^/]+))?/?’,’index.php?pagename=formation&formation_slug=$matches[2]&formation_id=$matches[4]’,’top’); add_rewrite_tag(‘%formation_slug%’,'([^&]+)’); add_rewrite_tag(‘%formation_id%’,'([^&]+)’); } This…