Only the first checkbox is set from a listview by clicking anywhere in the item

Good morning. I'm new to the forum and a newbie to android. I created a ListView through a Base Adapter, with checkbox selectable, so far so good. But when I click anywhere on an item, only the checkbox of the first item is set. As in the image, I clicked somewhere on the second item and the checkbox of the first one was set. By simply clicking the checkboxes they are set normally.

I tried the forum but I did not find a solution. If you're sorry for the duplicate. Please, how can I solve this problem? My getView from my adapter.

    public View getView(final int position, View convertView, ViewGroup parent) {
    // TODO Auto-generated method stub
    if(convertView == null){
        LayoutInflater inflater = (LayoutInflater)contexto.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        convertView = inflater.inflate(R.layout.item_list_selected, null);
    }

    ImageView icone = (ImageView)convertView.findViewById(R.id.imageView1);
    TextView nome = (TextView)convertView.findViewById(R.id.myTextViewItemListNomeSelected);
    TextView fone = (TextView)convertView.findViewById(R.id.myTextViewItemListFoneSelected);
    CheckBox cbx = (CheckBox)convertView.findViewById(R.id.myCheckBoxItemListSelected);

    Contato contato = contactList.get(position);

    icone.setImageResource(contato.getImage());
    nome.setText(contato.getNome());
    fone.setText(contato.getTel());
    cbx.setChecked(contato.isCheck());

    cbx.setTag(contato);

    cbx.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            CheckBox check = (CheckBox)v;
            Contato ct = (Contato)v.getTag();
            ct.setCheck(((CheckBox)v).isChecked());

            if(check.isChecked()){
                if(! idSelecteds.contains(ct.getID())){
                    idSelecteds.add(ct.getID());
                }
            }else {
                if(idSelecteds.contains(ct.getID())){
                    idSelecteds.remove(ct.getID());
                }
            }
        }
    });
    return convertView;
}

The implementation of my OnItemClickListener performed this way.

list.setOnItemClickListener(this);

public void onItemClick(AdapterView<?> parent, View view, int position,
        long id) {
    // TODO Auto-generated method stub

    CheckBox cb = (CheckBox)findViewById(R.id.myCheckBoxItemListSelected);
    cb.setChecked(true);
}