excerpts not showing when date is post date

Hi,
Thanks a lot for your plugin, that I really appreciate. This is just to let you know that I couldn’t achieve to show the excerpts when adding posts of the same date as the current post.
I’m using the shortcode this way:

<?php echo do_shortcode( '[on_this_day before_title="<h3>" 
before_widget="<div class=onthisday>" 
after_widget="</div>" 
after_title="</h3>" 
title="Ce même jour, les autres années..." 
show_post_excerpt="true" 
show_post_date="true" 
use_post_date="true" ] ' );?>

Voilà… If you have any idea of what I might have done wrong…
Thanks for your attention,

Véronique