Checkboxes uncheck when list updates - Android

I have defined a task, which is just the a checkbox and a text together.

I also have a ListView of tasks that show correctly.

The problem is, when I scroll the list or when I try to add a new element to my list, all the checkboxes uncheck, but the text stays the same.

Here's what I have for getView in my TaskAdapter :

public View getView(int position, View convertView, ViewGroup parent) {
    Task task = getItem(position);
    LayoutInflater inflater = (LayoutInflater) getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    convertView = inflater.inflate(layoutID, parent, false);
    TextView textView = (TextView) convertView.findViewById(R.id.description);
    CheckBox checkBox = (CheckBox) convertView.findViewById(R.id.box);
    textView.setText(task.getDescription());
    checkBox.setActivated(task.getBox());
    return convertView;
}

Thanks in advance for any help :D