How to disable scrolling when inside a horizontal slide (Fullpage.Js)

I found this code on the net, but it is already locking at the beginning ... I would like to activate the script when it is inside the slide ...

$ .fn.fullpage ({     afterSlideLoad: function (anchorLink, index, slideAnchor, slideIndex) {         if (slideIndex === 0) {             $ .fn.fullpage.setAllowScrolling (true);         } else {             $ .fn.fullpage.setAllowScrolling (false);         }     } });