Et upload script

Jeg har dette script, men desvære virker det ikke :(
og jeg kan simple hen ikke finde ud af hvorfor :(
er der en som kan finde ud af hvorfor?


// $mydir = c:\html\Zapsite\images\user\test\30092003_0005.JPG
// $image_dir = ../images/user


  /* we're doing a submit */
  $form_data_name = $_FILES['fileUpload']['name'];
  $form_data_size = $_FILES['fileUpload']['size'];
  $form_data_type = $_FILES['fileUpload']['type'];

  IF(is_file($image_dir.$form_data_name)){
      unlink($image_dir.$form_data_name);
  }
 
  $mydir =$LOCAL_image_dir."\\".$_USEDCAT."\\".$form_data_name;
echo "--->".$mydir."<----";
  move_uploaded_file($_FILES['link']['tmp_name'], $mydir);

  switch ($_FILES['link']['error']){
  case 0:
    echo $_FILES['link']['name']."(".$_FILES['link']['size']." bytes) was uploadet.<br><br>";
    break;
  case 3:
    echo "Your upload did not finish for som reason.<br><br>";
    break;
  case 4:
    echo "The file was not uploadet.<br><br>";
    break;
  }