Expandablelistview with checkboxes change selected checkboxes

I have an Expandablelistview that I load from database some data and I put that data in with checkboxes, but the problem is, if I check something on group 1 and open group 0, the checked checkbox at group 1 become unchecked and the last checkbox at group 0 become checked.

My adapter:

public class ExpandableListCheckboxAdapter extends BaseExpandableListAdapter {
    private List<String> listFather;
    private HashMap<String, ArrayList<CheckBox>> listChildren;
    private LayoutInflater inflater;
    private SparseBooleanArray spa = new SparseBooleanArray();

    public ExpandableListCheckboxAdapter(Context context, List<String> listGroup, HashMap<String, ArrayList<CheckBox>> listData){
        this.listFather = listGroup;
        this.listChildren = listData;
        inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }

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

    @Override
    public int getChildrenCount(int groupPosition) {
        return listChildren.get(listFather.get(groupPosition)).size();
    }

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

    public String getGroupText(int groupPosition) {
        return listFather.get(groupPosition).toString();
    }

    @Override
    public Object getChild(int groupPosition, int childPosition) {
        return listChildren.get(listFather.get(groupPosition)).get(childPosition);
    }

    public String getChildText(int groupPosition, int childPosition) {
        return listChildren.get(listFather.get(groupPosition)).get(childPosition).getText().toString();
    }

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

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


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

    public boolean isChecked(int groupPosition, int childPosition) {
        return listChildren.get(listFather.get(groupPosition)).get(childPosition).isChecked();
    }


    @Override
    public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {
        ViewHolderGroup holder;

        if(convertView == null){
            convertView = inflater.inflate(R.layout.expandable_father, null);
            holder = new ViewHolderGroup();
            convertView.setTag(holder);

            holder.txvFatherList = (TextView) convertView.findViewById(R.id.txvFatherList);
        }
        else{
            holder = (ViewHolderGroup) convertView.getTag();
        }

        holder.txvFatherList.setText(listFather.get(groupPosition));

        return convertView;
    }

    @Override
    public View getChildView(final int groupPosition, final int childPosition, boolean isLastChild, View convertView, final ViewGroup parent) {
        String val = (String) getChildText(groupPosition, childPosition);
        final ExpandableListCheckboxAdapter.ViewHolderItem holder;

        if(convertView == null){
            convertView = inflater.inflate(R.layout.expandable_children_subject, null);
            holder = new ExpandableListCheckboxAdapter.ViewHolderItem();
            convertView.setTag(holder);
            holder.ckbChildrenSub = (CheckBox) convertView.findViewById(R.id.ckbChildrenSub);
            holder.ckbChildrenSub.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
                @Override
                public void onCheckedChanged(CompoundButton compoundButton, boolean b) {
                    if(holder.ckbChildrenSub.isChecked()){
                        if(universalVariables.subjects.containsKey(getGroupText(groupPosition))){
                            List<String> aux = new ArrayList<>();
                            aux = universalVariables.subjects.get(getGroupText(groupPosition));
                            if(!aux.contains(holder.ckbChildrenSub.getText().toString()))
                                aux.add(holder.ckbChildrenSub.getText().toString());
                            universalVariables.subjects.put(getGroupText(groupPosition), aux);
                        }
                        else{
                            List<String> aux = new ArrayList<>();                 
                            aux.add(holder.ckbChildrenSub.getText().toString());
                            universalVariables.subjects.put(getGroupText(groupPosition), aux);
                        }
                    }
                    else {
                        if (universalVariables.subjects.containsKey(getGroupText(groupPosition))) {
                            List<String> aux = new ArrayList<>();
                            aux = universalVariables.subjects.get(getGroupText(groupPosition));
                            if (aux.contains(getChildText(groupPosition, childPosition))) {
                                aux.remove(getChildText(groupPosition, childPosition));
                                universalVariables.subjects.put(getGroupText(groupPosition), aux);
                            }
                        }
                    }
                }
            });
        }
        else{
            holder = (ExpandableListCheckboxAdapter.ViewHolderItem) convertView.getTag();
        }

        holder.ckbChildrenSub.setText(val);

        return convertView;
    }

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

    class ViewHolderGroup {
        TextView txvFatherList;
    }

    class ViewHolderItem {
        CheckBox ckbChildrenSub;
    }
}

Method to load data from database:

private void loadSubjects(){
    //Use database
    for (int i = 0; i < disciplinas.size(); i++) {
        if (!listGroup.contains(disciplinas.get(i)))
            listGroup.add(disciplinas.get(i));
        int idGeneric = 0;
        ArrayList<CheckBox> auxList = new ArrayList<CheckBox>();
        databaseHelper = dbHelper.getInstance(this, DB_NAME);
        String generic = disciplinas.get(i);
        String query = "SELECT Assunto FROM Assunto WHERE Disciplina='" + generic + "'";
        Cursor c1 = databaseHelper.rawQuery(query);
        if (c1 != null && c1.getCount() != 0) {
            if (c1.moveToFirst()) {
                do {
                    String assunto = c1.getString(c1.getColumnIndex("Assunto"));
                    checkbox = new CheckBox(this);
                    checkbox.setText(assunto);
                    auxList.add(checkbox);
                    idGeneric = idGeneric + 1;
                } while (c1.moveToNext());
            }
        }
        if (c1 != null)
            c1.close();
        listData.put(disciplinas.get(i), auxList);
    }

    expCheckListView = (ExpandableListView) findViewById(R.id.elstvSub);
    checkAdapter = new ExpandableListCheckboxAdapter(Assuntos.this, listGroup, listData);
    expCheckListView.setAdapter(checkAdapter);
}

Children XML:

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

    <CheckBox
        android:id="@+id/ckbChildrenSub"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

</LinearLayout>

Father XML:

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

    <TextView
        android:id="@+id/txvFatherList"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textColor="#000"
        android:textSize="18dp"
        android:layout_marginLeft="33dp" />

</LinearLayout>