"Aucun résultat" returned after a website search even if the site language is "English"

Hello,
I don’t understand why I get "Aucun résultat" instead of "no results" when I search for a string in my SPIP website.
I checked the "Language Files" and I do have a Aucun résultat. No results found.
So why is it returning : "Aucun résultat" ?

Thanks for your help,
Roberto Santoro.