Form Post Radiolistbutton Value Twice.

I have a radio list button in a form wirh normal submitbutton.

The value that is POSTed when I click on submit button post the radio button value twice. One is empty


<?php echo $form->radioButtonList($model,'exposed_to',array(        3=>'On',



								     array('separator'=>' ',



)); ?>

The HTML generated is

<input type="hidden" name="advertisement[exposed_to]" value="" id="ytadvertisement_exposed_to">

<span id="advertisement_exposed_to">

<input id="advertisement_exposed_to_0" class="error" type="radio" name="advertisement[exposed_to]" value="3">

<label class="fire-toggle" for="advertisement_exposed_to_0" style="display:inline">On</label>

<input id="advertisement_exposed_to_1" class="error" type="radio" name="advertisement[exposed_to]" value="2">

<label class="fire-toggle" for="advertisement_exposed_to_1" style="display:inline">Off</label>

<input id="advertisement_exposed_to_2" class="error" type="radio" name="advertisement[exposed_to]" value="1">

<label class="fire-toggle" for="advertisement_exposed_to_2" style="display:inline">Neutral</label>


The POST values in Firebug is


advertisement[exposed_to]	2

saveButton	Save

The radio button filed in validation is required. The error message on form shows its blank

change your hidden element name. Radion button name , Hidden name are same.

The hidden element is generated by Yii. I guess I cannot change the names

It was my mistake thanks to room and ERROR404NOTFOUND. put unckechedValue=Null.

i still get error, what else to be trigger of this?