[Plugin: Yet Another Related Posts Plugin] YARPP 3.5.2b1

In my posts I receive this error
Fatal error: Call to undefined function wp_list_pluck() in /homepages/35/d298958434/htdocs/v2/wp-content/plugins/yet-another-related-posts-plugin/class-core.php on line 445

In the Plug-in Settings management console the same error
Post types considered:
Fatal error: Call to undefined function wp_list_pluck() in /homepages/35/d298958434/htdocs/v2/wp-content/plugins/yet-another-related-posts-plugin/class-core.php on line 445

I read similar errors in the forum, and upgraded to 3.5.1.b1 and now to 3.5.2b1 in the hope this would fix the error, but no luck yet

Unfortunately the site was made for me by a developer who I lost contact with, and I’m happy with the WP interface, but am no coder!

If there’s anything obvious I can find and Edit in the code, I’d be confident to to that, but can’t debug it myself! Help!

Jeremy
See http://www.positivetv.tv/news then click a post to get the error
Thanks!

http://wordpress.org/extend/plugins/yet-another-related-posts-plugin/