Hello Geni Team:
I have this document
http://www.geni.com/documents/view?doc_id=6000000030870971327#
I have tried to add projects. I could find and select the project from the project list, but after I select the project, about two seconds after, Geni display the message "You do not have permission to add that document to projects." and remove the project from the document.
Now, if you go to the document page, you will see the projects in the list. This is because I had to go to the projects themselves and add the documents there. So, at the end I succeeded in having projects assigned to the document, but through an indirect fashion.