BuddyPress.org

Hello,
I would like to customize activation email content. I have already modified bp-custom.php and have changed the text in the activation email.
However, when it is received in the mailbox, “WordPress” is indicated in the field “From” instead of the website name. I am not sure how I can change it to the website name ’cause it seems to me that this code:
$from_name = $site_name . "<$admin_email>" ;
should work exactly as I need. And yet, it doesn’t.
How can I fix it?