Can't apply Ken Burns effect to a photo in my slideshow

The photo I'm referring to is a vertical panorama. Whenever my slideshow comes up to this photo the latter is simply stuck while the music plays in background. It waits for the time preset as the default which is viewable when opening settings. I can't grasp why. Another vertical panoramic photo displays Burns effect as expected. I viewed Info of each and haven't noticed nothing eye-catching other than difference in resolution and size that would give a slightest clue.

See the pics below.

iPhoto 9.4.3, hardware and OS X version as indicated at the bottom