The basic thing first:
Did you both send and receive to the Internet and was this project included in send/receive? If you go to "send/receive projects" in the main menu you can see what the destination is and if the project in question is selected.
(Or if you are both local to each other you could use send/receive by USB or network location. But are you both sending and receiving to the same USB or the same network folder).
If you are indeed sending and receiving this project to one another, send in a problem report in "Give Feedback" in the main menu, and tell us the project, and we can then investigate further.