I do not know enough about your card to be too specific, but here goes. Most cards I am aware of use a four digit pin, there is such a beast as a six digit pin in some countries, but I almost always see a four digit pin discussed, and if your card uses four, that what the terminal is expecting to see.
I have a true chip and pin issued by Citi for business, I have a four digit pin, and have used it in Germany, I would find it odd that France would go their own way and require only a six digit, but then they are French.
As for your card, it is difficult to say whether it is even a chip and pin, you may have the chip, and you may have a pin, but like another card I have, it may only be chip and signature, and the pin only for cash advance. As has been noted, any bank seems to be a poor source of info. I guess one question that might help...when you received your card, were you required to set up a PIN prior to activating? or was it done after the fact?
I will add, even with a chip and pin, you will likely still be asked for a signature as that seems to be primary on most US cards, and even then, the old mag strip cards still are accepted,. Trust that if they want your money, they will get it to work.