When Open Graph tags are added or updated on a page, it can take Facebook a few days to detect the changes. You can use the "Scrape Now" button in their Open Graph Debug tool below to force Facebook to update it's cache immediately:
developers.facebook.com/tools/debug/shar...umatismes-de-l-ongle
That page also lets you see what Facebook sees for your page, which is very helpful.
I hope that helps explain, but if you need anything else, let me know.
Thanks,
Alex
Sharing problem
