Vegas Movie Studio Slideshow Generator Can't Save?

Do you happen to know if I can save a slideshow in the process of creation? I'm adding lots of photos & I like moving them around in the slideshow creator before I "Create" the slideshow, adding it to the timeline. I added photos to the slideshow generator, moved a few around to the right place and then selected Save Project. I exited Vegas, loaded it back up and the slideshow generator was empty of all the photos I added. That means I would need to do all slideshow manipulation in one sitting. Not being able to save this effort in progress would be a major pitfall. Am I missing something?