Catch-box : pbs with French translation file

Hi, Thanks for your free Catch-box theme ! Everything works fine, except the translation. I found the French translation files in the catch-box/language/ folder. Two problems : 1 - some texts remain in English although a French equivalent is provided in the fr_FR.po file --> can't figure out why only some parts of the translation file are taken into account. 2 - I tried changing French translations in the fr_FR.po file, just to see if the changes are taken into account, but my changes are not displayed on the site --> why ? (say I wrote "pas de commentaire" instead of "aucun commentaire"). Can you please help ? Thanks Corinne