404 Error when uploading files with Uploadify on WordPress

I recently installed uploadifive on my site http://tradersprinting.com/contact/send-file-2/ , and am experiencing a 404 error every time that I attempt to upload a file.

The site is powered by the WordPress Content Management System, and the site is hosted on 1&1. The uploadify files are stored in the directory: “http://tradersprinting.com/wp-content/themes/traders/uploadify”. The WordPress function “bloginfo(‘template_directory’)” returns “http://tradersprinting.com/wp-content/themes/traders/”. Everything is currently at “factory settings” without any adjustments, save the snippet of code I am attaching below:

Code on the Page http://tradersprinting.com/contact/send-file-2/

  <?php
    chmod("wp-content/themes/traders/uploads/",0777);
    chmod("wp-content/themes/traders/uploadify/uploads/",0777);
  ?>
  <script src="<?php bloginfo('template_directory'); ?>/uploadify/jquery.min.js" type="text/javascript">
  </script>
  <script src="<?php bloginfo('template_directory'); ?>/uploadify/jquery.uploadifive.min.js" type="text/javascript">
  </script>
  <link rel="stylesheet" type="text/css" href="<?php bloginfo('template_directory'); ?>/uploadify/uploadifive.css">
  <style type="text/css">
    body {
      font: 13px Arial, Helvetica, Sans-serif;
    }
    .uploadifive-button {
      float: left;
      margin-right: 10px;
    }
    #queue {
      border: 1px solid #E5E5E5;
      height: 177px;
      overflow: auto;
      margin-bottom: 10px;
      padding: 0 3px 3px;
      width: 300px;
    }
  </style>
  <form>
    <div id="queue">
    </div>
    <input id="file_upload" name="file_upload" type="file" multiple="true">
    <a style="position: relative; top: 8px;" href="javascript:$('#file_upload').uploadifive('upload')">Upload Files</a>
  </form>
  <script type="text/javascript">
    <?php $timestamp = time();?>
      $(function() {
      $('#file_upload').uploadifive({
        'auto'             : false,
        'checkScript'      : 'check-exists.php',
        'formData'         : {
          'timestamp' : '<?php echo $timestamp;?>',
          'token'     : '<?php echo md5('unique_salt' . $timestamp);?>'
        },
        'queueID'          : 'queue',
        'uploadScript'     : 'uploadifive.php',
        'onUploadComplete' : function(file, data) { console.log(data); }
      });
    });
  </script>

My copy of uploadifive.php

<?php
/*
UploadiFive
Copyright (c) 2012 Reactive Apps, Ronnie Garcia
*/

// Set the uplaod directory
$uploadDir = '/uploads/';

// Set the allowed file extensions
$fileTypes = array('jpg', 'jpeg', 'gif', 'png'); // Allowed file extensions

$verifyToken = md5('unique_salt' . $_POST['timestamp']);

if (!empty($_FILES) && $_POST['token'] == $verifyToken) {
    $tempFile   = $_FILES['Filedata']['tmp_name'];
    //  Commenting out this line as a potential bugfix for 404 error
    //$uploadDir  = $_SERVER['DOCUMENT_ROOT'] . $uploadDir;
    $uploadDir = "/wp-content/themes/traders/uploadify/uploads";
    $targetFile = $uploadDir . $_FILES['Filedata']['name'];

    // Validate the filetype
    $fileParts = pathinfo($_FILES['Filedata']['name']);
    if (in_array(strtolower($fileParts['extension']), $fileTypes)) {

        // Save the file
        move_uploaded_file($tempFile, $targetFile);
        echo 1;

    } else {

        // The file type wasn't allowed
        echo 'Invalid file type.';

    }
}
?>

I have created an “uploads” directory in every branch of the directory tree starting from the root, and including one at every step of the way down to the sample uploadify directory, but none of them receive files.

I love the program, and I think the designer has done a stellar job, but I would really like for the product to work, especially after investing! Please help!