flickr photo embed no longer works

Hello,
some weeks ago I correctly installed and setup oEmbed in my Drupal 7 installation , so i was able to embed youtube videos and flickr photos.

Then suddenly flickr stopped to work and couldn't make it work again, while youtube continue to embed correctly.

In embed test tab, with a flickr photo link (for example: https://www.flickr.com/photos/campusbiomedico/16361473946/) i get this error:

https://www.flickr.com/photos/campusbiomedico/16361473946/ is not valid oEmbed URL

I setup a test environment with a fresh oembed installed (http://brandedcontent.it/temp)

what could be the problem?

thank you,
alessandro