Unable To Get Combo Box Value To Save?

I am new to YII. I have form which is used "Role" combo box (from model there is method). When I store in db , the value is always 0. The html is below

<div class="row">
	<?php echo $form->labelEx($model,'userType'); ?>
        <?php echo $form->dropDownList($model,'userType', $model->getUserTypeOptions()); ?>        
	</div>

and then my model is

public function getUserTypeOptions()
        {
           return array(
               '1' => 'Administrator',
               '2' => 'Team Member'
           ); 
        }
             

How to resolve this problem?