Formit checkboxes. Documentation example doesn't work with Template chunk

 <label>
        Colors:[[+fi.error.colors]]
        <input type="hidden" name="colors[]" value="" />
    </label>
    <ul>
      <li>
        <label><input type="checkbox" name="colors[]" value="red" [[!+fi.colors:FormItIsChecked=`red`]] /> Red</label>
      </li>
      <li>
        <label><input type="checkbox" name="colors[]" value="blue" [[!+fi.colors:FormItIsChecked=`blue`]] /> Blue</label>
      </li>
      <li>
        <label><input type="checkbox" name="colors[]" value="green" [[!+fi.colors:FormItIsChecked=`green`]] /> Green</label>
      </li>
    </ul>