problem with setColumnCountPortrait function

[bkhezry]

I use this code to implement loading more data with MaterialList.
it's work when mListView.setColumnCountPortrait(1); but when I set it 2 for example, function findFirstVisibleItemPosition return -1 all the time. any suggestion?

 mLayoutManager = (LinearLayoutManager) mListView.getLayoutManager();
        mListView.addOnScrollListener(new RecyclerView.OnScrollListener() {
            @Override
            public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
                if (dy > 0) //check for scroll down
                {
                    visibleItemCount = mLayoutManager.getChildCount();
                    totalItemCount = mLayoutManager.getItemCount();
                    pastVisiblesItems = mLayoutManager.findFirstVisibleItemPosition();
                    if (loading) {
                        if ((visibleItemCount + pastVisiblesItems) >= totalItemCount) {
                            loading = false;
                            Log.v("...", "Last Item!");
                            LoadMoreData();
                        }
                    }
                }
            }
        });