[Plugin: Yet Another Related Posts Plugin] YARPP Error in syntax in Error.log

I keep getting the following error in my error.log. Can you please tell me why this is happening or how I can fix? Thanks a bunch in advance.

[14-Sep-2010 01:04:04] WordPress database error You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ‘) AND wp_posts.post_type IN (‘post’) and post_date > date_sub(now(), interval 18′ at line 1 for query SELECT SQL_CALC_FOUND_ROWS wp_posts.* FROM wp_posts WHERE 1=1 AND wp_posts.ID in () AND wp_posts.post_type IN (‘post’) and post_date > date_sub(now(), interval 18 month) ORDER BY score DESC limit 5 made by require, require_once, include, get_sidebar, locate_template, load_template, require_once, include, related_posts, yarpp_related, WP_Query->query, WP_Query->get_posts, W3_Db->query