expandablelistview中自定义的child无法点击

写了一个自定义的expandablelistview
group设置监听事件，能被点击
child setOnChildClickListener()无反应 什么原因？？？

下面是适配器中getchildView()的函数
试了一下 把return换成title(title是自定义布局中的一个textview) 可以进行点击
怎么回事？？？？

        public View getChildView(int groupPosition, int childPosition,
                boolean isLastChild, View convertView, ViewGroup parent) {
            View view = convertView;
            if (view == null) {
                //LayoutInflater inflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
                LayoutInflater inflater = LayoutInflater.from(getActivity());
                view = inflater.inflate(R.layout.childitem, null);
            }
            final TextView title = (TextView) view
                    .findViewById(R.id.child_text);
            title.setText(childData.get(groupPosition).get(childPosition)
                    .get("child_text1").toString());
            final TextView title2 = (TextView) view
                    .findViewById(R.id.child_text2);
            title2.setText(childData.get(groupPosition).get(childPosition)
                    .get("child_text2").toString());
            final TextView title3 = (TextView) view
                    .findViewById(R.id.child_text3);
            title3.setText(childData.get(groupPosition).get(childPosition)
                    .get("child_text3").toString());            
            return view;
        }


isChildSelectable()函数已设为true
         public boolean isChildSelectable(int groupPosition, int childPosition) {
            return true;
        }