BerryPro : How to customize meta tag description and meta tag abstract in the homepage with drupal custom module metatag ?

Hello,
I would like to optimize our SEO by adding customized meta tag description and meta tag abstract in the homepage of our Berrypro theme site under Drupal 7.
I already did it for specific pages with Drupal Module "Metatag". If this module works well with specific pages (based upon path), I don't succeed in doing it with the homepage.
Can anyone help me to find an issue ?
Thanking you in advance,
Best regards,
Corinne