CheckBox in child of exapndablelistview (android)

Problem is with checkbox. When user click on child, app should show toast message on which child user clicked. It works fine if I click on textview of child, but when i click on checkbox, nothing heppend. Also when I click on child item, I want that my checkbox change state. Do you see something that I can't see. Here is my code for main activity

private ExpandableAdapter adapter;
private ExpandableListView expandableList;
private List<Pitanja> pitanjas = new ArrayList<Pitanja>();
private ArrayList<Pitanja> listaPitanja = new ArrayList<Pitanja>();
private List<Odgovor> odgovors = new ArrayList<Odgovor>();
public static HashMap<Integer, Integer> pitanjaa;
private Intent intent;
private ProgressDialog pDialog;
private TextView output;
private List<Ispit> ispitList;
private String pozicija;
private Button posalji;

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

    output = (TextView) findViewById(R.id.ispit_datum);
    output.setMovementMethod(new ScrollingMovementMethod());
    pitanjaa = new HashMap<Integer, Integer>();
    posalji = (Button) findViewById(R.id.posaljiIspitButton);
    posalji.setOnClickListener(this);

    generateData();
    initEx();

    intent = getIntent();
    RequestPackage p = new RequestPackage();
    p.setUri("http://ift.tt/1shyoaJ");
    p.setMethod("POST");
    p.setParam("id_kolegij", intent.getStringExtra("id_predmeta"));
    Log.i("Saljem podatke ", intent.getStringExtra("id_predmeta"));
    MyTask task = new MyTask();
    task.execute(p);


}

private void updateDisplay(){
    Collections.shuffle(ispitList);
    output.setText(String.valueOf(ispitList.get(0).getId()));
    MyRequest task = new MyRequest();//this works fine
    RequestPackage r = new RequestPackage();//works
    r.setMethod("POST");//works
    r.setUri("http://ift.tt/14IgmV4");//works
    r.setParam("id_kolegij", output.getText().toString());//works
    task.execute(r);

}

private void initEx(){
    adapter = new ExpandableAdapter(IspitActivity.this, listaPitanja);
    expandableList = (ExpandableListView) findViewById(R.id.expandableIspitListView);
    expandableList.setAdapter(adapter);
    for (int i=0;i<adapter.getGroupCount();i++){
        expandableList.collapseGroup(i);
    }
    expandableList.setOnChildClickListener(new OnChildClickListener(){

        @Override
        public boolean onChildClick(ExpandableListView arg0, View arg1,
                int arg2, int arg3, long arg4) {
            // TODO Auto-generated method stub
            Toast.makeText(getApplicationContext(), "Klikno si na " + adapter.getChild(arg2, arg3).getText() + " " + adapter.getChild(arg2, arg3).getTocan_netocan(), Toast.LENGTH_SHORT).show();
            if (Integer.parseInt(adapter.getChild(arg2, arg3).getTocan_netocan()) == 0)
                pitanjaa.put(arg2, arg3);
            Log.i("pitanja koja si odgovorio su", pitanjaa.toString());
            adapter.getChild(arg2, arg3).setSelected(true);
            return true;
        }

    });
}

private void generateData(){
    Pitanja p;
    for (int i=0;i<pitanjas.size();i++){
        ArrayList<Odgovor> od = new ArrayList<Odgovor>();
        for (int z=0;z<odgovors.size();z++){
            if (odgovors.get(z).getId_pitanja().contains(String.valueOf(pitanjas.get(i).getId()))){
                od.add(odgovors.get(z));
            }
        }
        pozicija = pitanjas.get(i).getText();
        p = new Pitanja(i, pozicija, od);
        listaPitanja.add(p);
    }

}

private class MyTask extends AsyncTask<RequestPackage, String, List<Ispit>>{

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        pDialog = new ProgressDialog(IspitActivity.this);
        pDialog.setMessage("Dobavljam podatke...");
        pDialog.setCancelable(false);
        pDialog.show();
    }

    @Override
    protected List<Ispit> doInBackground(RequestPackage... params) {
        String content = HttpManager.getData(params[0]);
        ispitList = JSONParser.parseIspit(content.substring(1, content.length()-1));
        Log.i("Parsirano izgleda sljedeci", content.substring(1, content.length()-1));
        return ispitList;
    }
    @Override
    protected void onPostExecute(List<Ispit> result) {
        super.onPostExecute(result);
        pDialog.dismiss();
        updateDisplay();
    }

}

@Override
public void onClick(View view) {


    Intent intent = new Intent(getApplicationContext(), PregledActivity.class);
    startActivity(intent);

}

}

Here is my expandablelistview adapter

public class ExpandableAdapter extends BaseExpandableListAdapter{
LayoutInflater inflater;
 private List<Pitanja> groups;
 public ExpandableAdapter(Context context,List<Pitanja> groups) {
 super();
  this.groups=groups;
  inflater= (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
 }
 public void addItem(Odgovor child,Pitanja group) {
  if(!groups.contains(group)) {
   groups.add(group);
  }
  int index=groups.indexOf(group);
  ArrayList<Odgovor> ch=groups.get(index).getOdgovors();
  ch.add(child);
  groups.get(index).setOdgovors(ch);
 }
    public Odgovor getChild(int groupPosition, int childPosition) {
     ArrayList<Odgovor> ch=groups.get(groupPosition).getOdgovors();
        return ch.get(childPosition);
    }   
    public long getChildId(int groupPosition, int childPosition) {
        return childPosition;
    }    
 @Override
 public int getChildrenCount(int groupPosition) {
  ArrayList<Odgovor> ch=groups.get(groupPosition).getOdgovors();
  return ch.size();
 } 
    public View getChildView(int groupPosition, int childPosition, boolean isLastChild,
            View convertView, ViewGroup parent) {
     Odgovor child= (Odgovor) getChild(groupPosition,childPosition);
     TextView childName=null;
     CheckBox cb = null;
     if(convertView==null) {
         convertView=inflater.inflate(R.layout.child_item, null);         
     }
     childName=(TextView) convertView.findViewById(R.id.textview_child_item);
     childName.setText(child.getText());
     cb = (CheckBox) convertView.findViewById(R.id.checkbox_child_item);
     if (child.isSelected())
         cb.setChecked(true);
  return convertView;
    }
    public Pitanja getGroup(int groupPosition) {
        return groups.get(groupPosition);
    }
    public int getGroupCount() {
        return groups.size();
    }
    public long getGroupId(int groupPosition) {
        return groupPosition;
    }
    public View getGroupView(final int groupPosition, boolean isExpanded, View convertView,
            ViewGroup parent) {
     TextView groupName = null;
     Pitanja group=(Pitanja) getGroup(groupPosition);
     if(convertView==null) {
       convertView=inflater.inflate(R.layout.parent_item, null);        
     }
     groupName=(TextView) convertView.findViewById(R.id.parent_item);
     groupName.setText(group.getText());
        return convertView;
    }
    public boolean isChildSelectable(int groupPosition, int childPosition) {
        return true;
    }
    public boolean hasStableIds() {
        return true;
    }
    }

my child view

 <LinearLayout xmlns:android="http://ift.tt/nIICcg"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal" >
<CheckBox
    android:id="@+id/checkbox_child_item"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:focusable="false" />
<TextView
    android:id="@+id/textview_child_item"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" />
</LinearLayout>

If I changle focusable of my checkbox, it doesn't work too. Someone have idea