why Loadmore call only once 

why Loadmore call only once ,my code is :
waterfallView.setOnLoadMoreListener(new OnLoadMoreListener() {

			@Override
			public void onLoadMore() {
				// TODO Auto-generated method stub
				Toast.makeText(MainActivity.this, "more", 2000).show();

				List<String> moreList = new ArrayList<String>();

				moreList.add("http://f.hiphotos.baidu.com/image/pic/item/8601a18b87d6277f1b4b883e2a381f30e924fc5f.jpg");

				adapter.addFootList(moreList);
				waterfallView.onLoadMoreComplete();
			}
		});

the adapter is :
public void addFootList(List<String> moreList) {
		this.list.addAll(moreList);
		this.notifyDataSetChanged();
	}
who can help me,thanks.