Problem with Photos

I really don't understand what happened but...

I'm working on making something in iMovie and the first few photos I add worked great-- I want the "Ken Burns" effect on them and it added it right away. Now, however, it won't add the effect at all and when I go to apply it, it deletes the photo; if it doesn't delete the photo, it doesn't apply it.

My only guess is that it's treating the photots like video stills. How do I fix this? Thanks!