Final question for Hoang Ngo concerning child theme settings

Regarding thread https://premium.wpmudev.org/forums/topic/can-i-append-a-source-to-the-subject-line#post-681421 , it works GREAT!

Just wondered if you did anything other than copy text into functions.php and activate.

Reason I ask is that I tried the same procedure in a different site and it didn't work correctly.

Thanks again for your help!!!
ed