passing variable to url

Hi, My first post so please excuse if im ake any mistakes.

I have a drop down that I am getting a post variable from with i am then trying to append an URL with.

It works but only for the first option.

Any help much appreciated.

When I echo the $pagelink it shows the correct value but when I add it to the header location it just goes to the homepage of the site (except the first option)!

My index.php:

<?php
// connect to db
mysql_connect ("xxxxxx", "xxxxx","")  or die (mysql_error());
mysql_select_db ("xxxxxx");

//query
$sql = mysql_query('SELECT product_id, name FROM  CubeCart_inventory');
$models = array();
while ($row = mysql_fetch_array($sql)){
    $models[] = $row;
}
?>

<form action="config.php" method="POST">
  <select name="battery">
  <?php
  foreach ($models as $model) {
  ?>
    <option value="<?php echo $model['name']?>"><?php echo $model['name']?></option>
  <?php
  }
  ?>
  </select>
  <input type="submit" name="submit" value="Submit" />
</form>

my config.php:

<?php

//var_dump($_REQUEST); 
 	$name = $_POST['battery'];
	$pagelink = str_replace(" ","-",$name);
	$pagelink = strtolower($pagelink);
	$pagelink = $pagelink.".html";
	
header ('Location: http://localhost/carrotcycles/test-category/'$pagelink);
?>