French no working

Hello, is there anyway to make this work with fr language
error : not found : mywebsite/wp-content/plugins/wp-invoice-4.2.2/lib/ui/notifications-wp-invoice_page_wpi_page_manage_invoice.php

have try to change wp-invoice-fr_FR.po by wp-Invoice-fr_FR.po, working but everything is in English

Thx