[Plugin: Slideshow Gallery Pro] Short of thumbnail

Hi,
I’ve installed this one, almost works well except the thumbnail. I uploaded 8 photos, but when publish, it does show 3 thumbnails only. The other photos appears when I click Next image button.

Could you please help to check the issue?
Thanks you very much,

My test site is: http://powerlab.vn/test11/?p=4972

http://wordpress.org/extend/plugins/slideshow-gallery-pro/