I am trying to create a mathematical formula involving 2 numbers coming from 2 different custom fields (both numbers fields).

This is how my formula goes : ${Quotes.Nombre d'utilisateurs}*${Quotes.Prix par utilisateur}

Translation : ${Quotes.Number of users}*${Quotes.Price per user}

My Zoho CRM is in French, and when I try push the validation button, I get a nasty error window saying : "Erreur. Manque de cotes." Which in fact, doesn't mean anything in French, and furthermore doesn't give me any information about what is wrong in my formula.

Cloud somebody tell me what is wrong with my mathematical formula ?