My photos won't play in iMovie

I'm trying to get my photos from iPhoto to play in iMovie. They show up on the camera icon and I can drag them to the timeline where they also show up, but when I try to play them, it's just a black screen. They are JPEGs. I tried converting them to PNGs with no luck. I tried dragging them from the desktop with no luck. I tried rebuilding the iPhoto library with no luck. I am running iMovie '09 and iPhoto 9.6.1 on a Mac Air.