help with sub_groups

Hi,

I am using latest 0.8.61 and was trying to follow example in "Managing subgroups of books" :
http://manual.calibre-ebook.com/sub_groups.html (looks like help is outdated)
but so far with no success. It show as below, without

Category (my name for tag)
[1]Computers.ActiveDirectory
[3]Computers.Unix

and I was expecting

Category (my name for tag)
[4]Computers
[1]ActiveDirectory
[3]Unix


I searched the forum, but could not find relevant topics.

Please let me know if anything I should review or post here to clarify my issue.

Thank you
edabxv