Android Expandable List not working inside fragment viewpager

I want to have an expandable list box inside a viewPager. The viewPager domain is a fragment. I used this tutorial: http://www.androidhive.info/2013/07/android-expandable-list-view-tutorial/

this is my snippet code:

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ExpandableListView;

public class Resturant_menu extends Fragment {
ExpandableListAdapter listAdapter;
ExpandableListView expListView;
List<String> listDataHeader;
HashMap<String, List<String>> listDataChild;
View v; 

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) {
    v = inflater.inflate(R.layout.resturantmenu, container, false);
    return v;
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);

     // get the listview
   expListView = (ExpandableListView) v.findViewById(R.id.expandableListView1);

   // preparing list data
   prepareListData();

   listAdapter = new ExpandableListAdapter(getActivity(), listDataHeader, listDataChild);

   // setting list adapter
   expListView.setAdapter(listAdapter);

}
 private void prepareListData() {
        listDataHeader = new ArrayList<String>();
        listDataChild = new HashMap<String, List<String>>();

        // Adding child data
        listDataHeader.add("Top 250");
        listDataHeader.add("Now Showing");
        listDataHeader.add("Coming Soon..");

        // Adding child data
        List<String> top250 = new ArrayList<String>();
        top250.add("The Shawshank Redemption");
        top250.add("The Godfather");
        top250.add("The Godfather: Part II");
        top250.add("Pulp Fiction");
        top250.add("The Good, the Bad and the Ugly");
        top250.add("The Dark Knight");
        top250.add("12 Angry Men");

        List<String> nowShowing = new ArrayList<String>();
        nowShowing.add("The Conjuring");
        nowShowing.add("Despicable Me 2");
        nowShowing.add("Turbo");
        nowShowing.add("Grown Ups 2");
        nowShowing.add("Red 2");
        nowShowing.add("The Wolverine");

        List<String> comingSoon = new ArrayList<String>();
        comingSoon.add("2 Guns");
        comingSoon.add("The Smurfs 2");
        comingSoon.add("The Spectacular Now");
        comingSoon.add("The Canyons");
        comingSoon.add("Europa Report");

        listDataChild.put(listDataHeader.get(0), top250); // Header, Child data
        listDataChild.put(listDataHeader.get(1), nowShowing);
        listDataChild.put(listDataHeader.get(2), comingSoon);
    }

      

        
        
        
      

    

}

this is the ExpandableListAdapter:

import java.util.HashMap;
import java.util.List;

import android.content.Context;
import android.graphics.Typeface;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseExpandableListAdapter;
import android.widget.TextView;

      

        
        
        
      

    

Public class ExpandableListAdapter extends BaseExpandableListAdapter {

private Context _context;
private List<String> _listDataHeader; // header titles
// child data in format of header title, child title
private HashMap<String, List<String>> _listDataChild;

public ExpandableListAdapter(Context context, List<String> listDataHeader,
        HashMap<String, List<String>> listChildData) {
    this._context = context;
    this._listDataHeader = listDataHeader;
    this._listDataChild = listChildData;
}

@Override
public Object getChild(int groupPosition, int childPosititon) {
    return this._listDataChild.get(this._listDataHeader.get(groupPosition))
            .get(childPosititon);
}

@Override
public long getChildId(int groupPosition, int childPosition) {
    return childPosition;
}

@Override
public View getChildView(int groupPosition, final int childPosition,
        boolean isLastChild, View convertView, ViewGroup parent) {

    final String childText = (String) getChild(groupPosition, childPosition);

    if (convertView == null) {
        LayoutInflater infalInflater = (LayoutInflater) this._context
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        convertView = infalInflater.inflate(R.layout.list_item, null);
    }

    TextView txtListChild = (TextView) convertView
            .findViewById(R.id.lblListItem);

    txtListChild.setText(childText);
    return convertView;
}

@Override
public int getChildrenCount(int groupPosition) {
    return this._listDataChild.get(this._listDataHeader.get(groupPosition))
            .size();
}

@Override
public Object getGroup(int groupPosition) {
    return this._listDataHeader.get(groupPosition);
}

@Override
public int getGroupCount() {
    return this._listDataHeader.size();
}

@Override
public long getGroupId(int groupPosition) {
    return groupPosition;
}

@Override
public View getGroupView(int groupPosition, boolean isExpanded,
        View convertView, ViewGroup parent) {
    String headerTitle = (String) getGroup(groupPosition);
    if (convertView == null) {
        LayoutInflater infalInflater = (LayoutInflater) this._context
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        convertView = infalInflater.inflate(R.layout.list_group, null);
    }

    TextView lblListHeader = (TextView) convertView
            .findViewById(R.id.lblListHeader);
    lblListHeader.setTypeface(null, Typeface.BOLD);
    lblListHeader.setText(headerTitle);

    return convertView;
}

@Override
public boolean hasStableIds() {
    return false;
}

@Override
public boolean isChildSelectable(int groupPosition, int childPosition) {
    return true;
}

      

        
        
        
      

    

}

this action:

public class Showit extends FragmentActivity {
private PagerSlidingTabStrip tabs;
private ViewPager pager;
private MyPagerAdapter adapter;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.showit);

    tabs = (PagerSlidingTabStrip) findViewById(R.id.tabs);
    pager = (ViewPager) findViewById(R.id.pager);
    adapter = new MyPagerAdapter(getSupportFragmentManager());
    pager.setAdapter(adapter);
    final int pageMargin = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 4, getResources().getDisplayMetrics());
    pager.setPageMargin(pageMargin);
    tabs.setViewPager(pager);
}

public class MyPagerAdapter extends FragmentPagerAdapter {
    private final String[] TITLES =  getResources().getStringArray(R.array.tabresturan);;

    public MyPagerAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public CharSequence getPageTitle(int position) {
        return TITLES[position];
    }

    @Override
    public int getCount() {
        return TITLES.length;
    }

    @Override
    public Fragment getItem(int arg0) {
        Fragment fragment=null;
        fragment=new Resturant_menu();
        return fragment;
    }

}

      

        
        
        
      

    

this is the layout:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <ExpandableListView
        android:id="@+id/expandableListView1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
         >
    </ExpandableListView>

      

        
        
        
      

    

this is what i get:

instead of this:

I don't get any error, I added all the classes and layout that was specified.

Could you please help me to solve this problem? Thanks you