[Plugin: SB Child List] SQL errors

Hi, I get some SQL errors in Apache error log related to this plugin:

[08-Feb-2012 12:35:43] 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 post_type = 'page'
			ORDER BY menu_order, post_title' at line 6 for query SELECT ID, post_title, post_type
			FROM wp_posts
			WHERE
				post_status = 'publish'
				AND post_parent =
				AND post_type = 'page'
			ORDER BY menu_order, post_title made by require, wp, WP->main, WP->query_posts, WP_Query->query, WP_Query->get_posts, apply_filters_ref_array, call_user_func_array, relevanssi_query, relevanssi_do_query, relevanssi_do_excerpt, apply_filters, call_user_func_array, do_shortcode, preg_replace_callback, do_shortcode_tag, call_user_func, sb_cl_filter_post, sb_cl_render_child_list

Apparently the $id variable sometimes gets to be empty.

http://ww.wp.xz.cn/extend/plugins/sb-child-list/