OnPageScrolled doesn't work on Android -

i know there similiar problems on stackoverflow none of these solutions worked me. want use method onpagescrolled, have set listner, adapter etc. still doesn't react. here code : implement method via :

public class chefviewactivity extends robofragmentactivity implements  viewpager.onpagechangelistener { 

then :

.... pagerindicator = new pagerindicator((linearlayout) findviewbyid(r.id.pagerindicator),             fragments.size());     fragmentadapter = new detailsfragmentadapter(getsupportfragmentmanager(), fragments,             pagerindicator);      viewpager = (viewpager) findviewbyid(r.id.pager);     viewpager.setadapter(fragmentadapter);     viewpager.setonpagechangelistener(pagerindicator);     viewpager.setoffscreenpagelimit(5);     pagerindicator.onpageselected(viewpager.getcurrentitem()); ..... 

the following code works me.

viewpager.setonpagechangelistener(new onpagechangelistener() {              @override             public void onpageselected(int arg0) {              }              @override             public void onpagescrolled(int arg0, float arg1, int arg2) {              }              @override             public void onpagescrollstatechanged(int arg0) {              }         });