Resize avatar if not in usergroup

[DragonBlade]

I'm attempting to code a function that will resize an existing custom avatar and save it to the custom avatars table for a user if that user no longer has permissions to use the size they are using.

PHP Code:

function check_avatar($user)
{
  global $vbulletin;
  $permissions = cache_permissions($user);
  // Check to see if user has a custom avatar or is over the limit
  $customavatar = $vbulletin->db->query_first("SELECT width, height FROM customavatar WHERE userid=" . $user['userid']);
  if (!$customavatar) {return true;}
  if (($customavatar['width'] < $user['permissions']['avatarmaxwidth']) AND ($customavatar['height'] < $user['permissions']['avatarmaxheight'])) {return true;}

  // If not, upload new avatar from the old image
  require_once(DIR . '/includes/class_upload.php');
  require_once(DIR . '/includes/class_image.php');
  $upload = new vB_Upload_Userpic($vbulletin);
  $upload->data =& datamanager_init('Userpic_Avatar', $vbulletin, ERRTYPE_STANDARD, 'userpic');
  $upload->image =& vB_Image::fetch_library($vbulletin);
  $upload->maxwidth = $user['permissions']['avatarmaxwidth'];
  $upload->maxheight = $user['permissions']['avatarmaxheight'];
  $upload->maxuploadsize = $user['permissions']['avatarmaxsize'];
  $upload->allowanimation = ($user['permissions']['genericpermissions'] & $vbulletin->bf_ugp_genericpermissions['cananimateavatar']) ? true : false;
  // Use the previous image URL
  $url = 'http://MYFORUMURL/image.php?u=' . $user['userid'];
  if (!$upload->process_upload($url)) {standard_error('MERGH!<br /><br />' . $url . '<br />' . $upload->fetch_error(), false);}
  return false;
} 

Unfortunately, it's telling me that it's an invalid file. >.> Of course, MYFORUMURL is my forum URL. This is the output I get from my Standard Error there:

MERGH!

http://MYFORUMURL/image.php?u=53492
Invalid File

Advice, please?