Flickr policy requires that when anyone direct links a Flickr photo to another site, they also link back the Flickr page of the photo. On each photo page, there is an arrow ("Share Photo" button) at the bottom right of each photo that provides the proper BBCode, and that's what you are supposed to use. They could be blocking your photos from appearing on this page because this page lacks the proper links.
I also have a free account on Flickr. Can you see my photos?