Related Listings not working

I installed the Responsive Coupon Theme version 6.6.3 and I can’t make it to display the related listings. I checked the Page Setup -> Content pages -> Listing Page Layout and it already contains at the end the [RELATED] shortcode, but no result.

Also, in General Settings -> Search/Listing Page -> Listing Page Settings is set for 3 items per page. No result.

I have more than one category with multiple coupons.

Any help? Any other settings to check?
Thx