Quick Tip: When working with BuddyPress, bp-custom.php is a file that you create for all of your custom BuddyPress code. It gets loaded with all the rest of BuddyPress automatically during each page load.

This file belongs in wp-content/plugins, not wp-content/plugins/buddypress. That can be confusing and may cost you some time if you’ve uploaded your changes to the wrong directory.