We have had the same problem In our experience the issue is with your bank's security program. They see a local charge in France, especially one run manually without the card present, and decline it because they know you are in Boston (they know all kinds of stuff...)
Our standard routine with Bank of America is to give Maud the credit card information, she runs it, it is declined. We call BofA and say "please approve the charge in France". We tell Maud to run it again. It is approved. She gets this all the time, and is very patient with the process.
You can short circuit this if your bank is on the ball by calling ahead and telling them you will be making a charge of "x" dollars in France, and to please pre-approve it. Sometimes this has worked for us--sometimes not.
Annapolis, MD, USA