Filter by post category does not work

I’m trying to show only particular future posts but including the numeric id for post categories doe not filter correctly. Once any id is entered then the list is blank. I’m finding the ID’s by examining the url from the admin display of the category
For instance, in this case I wold use 40
http://hulmehallschool.ismysite.co.uk/wp-admin/edit-tags.php?action=edit&taxonomy=category&tag_ID=40&post_type=post

– any pointers as to what I might be doing wrong, alternative approaches I could use – or is it a bug?

http://wordpress.org/plugins/special-recent-posts/