Hi,
"MON PANIER" is the official
VM - Shopping Cart module and it doesn't show product thumbnail by default. You are using our "FashionMart" template and FashionMart template has no influence on Virtuemart Shopping Cart module (some of our other templates have, but not "FashionMart"). So everything is normal in your website.
If you want to show the product thumbnail in the shopping cart module, you may consider take a look at our "Dropdown Shopping Cart" module:
www.flexiblewebdesign.com/Virtuemart-Modules/Virtuemart-DropDown-Shopping-Cart
Regards.
Support & Development