i have write this code in base.php

$Categories = array( '1' => 'Education',
'2' => 'Organisation',
'3' => 'Company'
);
$fieldChoose = new RadioField('to');
  foreach ( $Categories as $cat => $label )
{
$fieldChoose->addOption($cat, $label);
}
$fieldChoose->setRequired();
$fieldChoose->setLabel($language->text('event', 'add_form_to_label'));
$this->addElement($fieldChoose);

and in base_add.html

<tr class="ow_alt2">
<td class="ow_label">{label name='to'}</td>
<td class="ow_value">{input name='to'} <br /> {error name='to'}</td>
<td class="ow_desc ow_small">{text key='event+add_form_to_label'}</td>
</tr>

but it dont shoe any output...somebody please help me for this