Where is Xcode's Build and Archive command looking for its iTunes artwork?

I just found out about the Build and Archive option, and it looks very nice.

However, my application build with Build and Archive has a big question mark as its artwork in the Organizer window, instead of my nice iTunesArtwork file. I tried to have it in my project as PNG, JPG, with or without extension.

I probably missed something simple. Any idea? Where is the Build and Archive command looking for its iTunes artwork?

Thanks a lot.