The owner has probably set the photos to no downloads. see the link for info.
Actually you can work around this problem:
- Download and install firefox (http://www.mozilla.com/en-US/firefox/)
- Go to the flickr page.
- On your firefox menu: Tools -> Page Info -> Media
- Find the photograph and click “Save As” (bottom right).
However, as the previous person pointed out, the owner of the photograph has decided that they don’t want to share this picture in this fashion. Please respect the copyright and permissions that people set for their work.