Error with WP 3.5: wpdb::prepare()

Is there something in which anyone can help me? I got this code from theme-functions.php

// get all the custom field labels so we can match the field_name up against the post_meta keys
$sql = $wpdb->prepare(“SELECT field_label, field_name, field_type FROM “. $wpdb->prefix . “cp_ad_fields”);

warning like this
Warning: Missing argument 2 for wpdb::prepare(), called in C:\xampp\htdocs\classi\wordpress\wp-content\themes\ClassiPress\includes\theme-functions.php on line 314 and defined in C:\xampp\htdocs\classi\wordpress\wp-includes\wp-db.php on line 990

What to change in this?

http://ww.wp.xz.cn/extend/plugins/select-featured-posts/