Update query won't update, but doesn't show an error when run
<p>I'm currently working on a php user admin system for work. I'm able to create new users. I'm able to update the user account that I'm logged into--first name, last name, email, and password. I created a page that generates user’s information in a table. 
It shows user id, username, first name, last name, email address with a delete and edit link. The delete script works. The edit link goes to a form so I can update user info. The problem I'm having is: when I update the user’s information it's not updating it in the database. 
I can only update user’s information if I'm logged as that user. I'm using sessions, and I think it has something to do with my issues. Here's the code. This script is run after I press submit to update user information. Any help would be appreciated. Thanks.</p>

<pre><code>&lt;?php

require("connect.php");

if(empty($_SESSION['user'])) {
header("Location: ../hound/login.php");
die("Redirecting to ../hound/login.php");
}

 $array_value = array(
    ':email' =&gt; $_POST['email'],
    ':first_name' =&gt; $_POST['first_name'],
    ':last_name' =&gt; $_POST['last_name'],
    ':id' =&gt; $_POST['id']
  );

  $query = "UPDATE users 
    SET 
    email = :email,
    first_name = :first_name, 
    last_name = :last_name
    WHERE
      id = :id";

  try {
    $stmt = $db-&gt;prepare($query);
    $result = $stmt-&gt;execute($array_value);
  }
 catch(PDOException $ex) {
 die("Failed to run query: " . $ex-&gt;getMessage());
 }
 header("Location: users.php");
 die("Redirecting to users.php");

 ?&gt;
</code></pre>

<p>This is the form to edit user information. Once the submit button is pressed it runs the script above. Then returns to a page named users.</p>

<pre><code>&lt;?php

require("../scripts/common.php");


if(empty($_SESSION['user']))
{

header("Location: ../hound/login.php");


die("Redirecting to ../hound/login.php");
}

$query_parm = array(

':id' =&gt; $_GET['id']

);


$query = "

SELECT
*
FROM users 
WHERE 
id = :id
";


try
{
$stmt = $db-&gt;prepare($query);
$stmt-&gt;execute($query_parm);

 }
 catch (PDOException $ex)
 {

 die("Failed to run query: " . $ex-&gt;getMessage());

  }

 $rows = $stmt-&gt;fetchAll();


  ?&gt;

 &lt;form action="../scripts/edit_users.php" method="post"&gt;

  &lt;?php foreach($rows as $row): ?&gt;

  Username:&lt;br /&gt;
 &lt;b&gt;&lt;?php echo htmlentities($row['username'], ENT_QUOTES, 'UTF-8'); ?&gt;&lt;/b&gt;
 &lt;br /&gt;&lt;br /&gt;
 First Name:&lt;br /&gt;
 &lt;input type="text" name="first_name" value="&lt;?php echo htmlentities($row['first_name'], ENT_QUOTES, 'UTF-8'); ?&gt;" /&gt;
 &lt;br /&gt;&lt;br /&gt;
 Last Name:&lt;br /&gt;
 &lt;input type="text" name="last_name" value="&lt;?php echo htmlentities($row['last_name'], ENT_QUOTES, 'UTF-8'); ?&gt;" /&gt;
 &lt;br /&gt;&lt;br /&gt;
  E-Mail Address:&lt;br /&gt;
  &lt;input type="text" name="email" value="&lt;?php echo htmlentities($row['email'], ENT_QUOTES, 'UTF-8'); ?&gt;" /&gt;
   &lt;br /&gt;&lt;br /&gt;
   Password:&lt;br /&gt;
   &lt;input type="password" name="password" value="" /&gt;&lt;br /&gt;
   &lt;br /&gt;&lt;br /&gt;
   &lt;input type="submit" value="Update User" /&gt;
   &lt;a href="../scripts/users.php"&gt;Back&lt;/a&gt;&lt;br /&gt;
   &lt;?php endforeach; ?&gt;
</code></pre>