Featured post slider: wront thumbnail used

I am using "Post Thumbnail editor" plugin to get choice of thumbnails rather than the default middle of image. This works brilliantly in most places (like post listing being square subsets of the featured image). I would expect that the thumbnail chosen for the 976x313 would appear in the featured post slider. http://www.freerollmedia.com/ The featured post slider is choosing its own thumbnails it seems as some images are getting letterbox edges on the left and right. Which thumbnails are being chosen, and how do I get more control over them? Theme: Simple Catch