WP smush does not find my images on server

Hi

My images are stored on a different server than my wordpress. And it seems that wp smush can't find my images to smush it :disappointed:

For example it looks for :

/home/unbeaujour/public_html/www.leblogdelamechante.fr/images/2016/02/Collections-29-150x150.jpg

While it's actually images.leblogdelamechante.fr/images/2016/02/Collections-29-150x150.jpg

Can you help me with that ?