Shortcode doesn’t work

Hello,
I’m using (testing) the free version of this plugin to display some posts on my homepage.
I try to use this shortcode:
[recent_post_slider limit=”4″ design=”design-3″]
or this:
[recent_post_slider category=”xxx” design=”design-3″]
or anything else, but the slider doesn’t work well.
It show the slides (not ever), but doesn’t do as it is set.

In Post category i don’t see the label “[recent_post_slider category=”xxx”]” shown in the documentation, but only “Category ID”. Could it conflict?

Tips?