hi tibavo,
The slider is working fine in our demo site so it must work at your site too. Did you customize any code ? IF yes then that may cause the problem.
Go to any page or post
set the featured image which is at right hand side below the update / publish
view this url
http://awesomescreenshot.com/02d36myje7
In url(where there is website url) you may see post=16 or something like this number
So here the id is 16 so you paste this id number inside dashboard -> apperance -> theme -options -> featured post/page slider
you keep id in this way
view this link
http://awesomescreenshot.com/0fe36mzo9e
Thank you!
.
.