Since Version 3.6.1 the Footer don´t change to the modified date (”Aktualisiert am:”) because the If block always returns false.
I´m using this Script in Atahualpa 3.5.3 "Edit Post/Page Info Items" (FOOTER: Homepage, FOOTER: Multi Post Pages, FOOTER: Single Post Pages, FOOTER: "Page" Pages) to modify the Footer of Single Post Pages and it works fine.

PHP Code:

<?php if(strtotime($post->post_modified) - strtotime($post->post_date) > 86400)
{
echo “Aktualisiert am: ” ;
the_modified_date(’j. F Y’);
echo ” um ” ;
the_modified_time(’G:i’);
}
else
{
echo “Erstellt am: ” ;
echo get_the_date();
echo ” um ” ;
echo get_the_time();
} ?> | Autor: %author-nickname% | %tags-linked(’Tags: ‘, ‘, ‘, ‘ | ‘)% Kategorie: %categories-linked(’, ‘)% %edit(’ | ‘, ‘Bearbeiten’, ”)%

Regards
NB

edit bfa_post_parts.php (it's in the 'functions' folder) and change
in version 3.6.1 - line 176
in version 3.6.4 - line 171
from

	global $bfa_ata;

to

	global $bfa_ata, $post;

added to 3.6.5 TODO list (BUGFIX 364-06: Post Date does not work in 'FOOTER: xxxx' )

Thanks juggledad

now it works

I´m using now version 3.6.4 and there it´s also line 176 to change.

NB

true, unless you have applied BUGFIX 364-05, in which case it is line 171