Problem with photos posted to flickr

When I post an image to flickr and later want to move the photo to another project. They just don't move without error message.

I can select them and create a new project and select to have them moved to the new project. But then they seen to be copied to it.

Can't believe that this is intended behaviour.

Does someone have made the same experience and knows how to get around the problem?

Thx, Dietmar