validation problem with Dropdoen list

[eluser]Ram2810[/eluser]
Am trying to retain the value on postback if error occurs in the form .... when valiadtion fails i want the page should show the previous selected drop down value ... i followed as noted in user guide but there is no proper out put .... pls help me out ....

THE CODE

Code:

<form action="<?= base_url();?>users/registersubmit" method="post">
&lt;?php echo validation_errors('<p class="error">','</p>'); ?&gt;
<fieldset>
<legend><span>Login&nbsp;Credentials</span></legend>
<ol><li>
<label for="u_regtype" >Type of Registration</label>
<select id="u_regtype" name="u_regtype">
&lt;?php foreach ($regtypes as $regtype){
echo "<option value='".$regtype->id."'";echo set_select('u_regtype',$regtype->id).">".$regtype->rgt_name."</option>";}?&gt;  
</select>
</li><li>
<label for="u_username">User Name:<span class="require"><img src="&lt;?=asset_url()?&gt;css/design_images/required_star.gif" alt="required" /></span> </label>
&lt;input id="u_username" name="u_username" value = "&lt;?= set_value('u_username');?&gt;" class="text" type="text" /&gt;
</li><li>
<label for="u_pass">Password:<span class="require"><img src="&lt;?=asset_url()?&gt;css/design_images/required_star.gif" alt="required" /></span> </label>
&lt;input id="u_pass" name="u_pass" class="text" type="text" /&gt;
</li><li>
<label for="u_pass2">Re-enter Password:<span class="require"><img src="&lt;?=asset_url()?&gt;css/design_images/required_star.gif" alt="required" /></span> </label>
&lt;input id="u_pass2" name="u_pass2" class="text" type="text" /&gt;
</li></ol></fieldset>&lt;/form&gt;

I am not able to select the previous selected on returning to same page after producing errors