problems with thumb creation

[eluser]ebuoe[/eluser]
hello ,i intend to upload images and also create a thumb and move to the thumb folder at 1nce
,then relocate back to the home page ,everything seems to be work ecepte the thumb creation,and also moving it
$data['error'] = "";


$dir = "./images/uploads";
$new = "./images/uploads/thumbs";

$config['file_name'] = $user_id;
$config['upload_path'] = $dir;
$config['allowed_types'] = 'gif|jpg|png';
$config['max_size'] = '5000';
$config['max_width'] = '1000';
$config['max_height'] = '2000';

$this->load->library('upload', $config);

if ( ! $this->upload->do_upload())
{
$data['error'] = $this->upload->display_errors();

$this->load->view("c_user/i_craft_set_avatar",$data);
}
else
{
$data = array('upload_data' => $this->upload->data());


$config['image_library'] = 'gd2';
$config['source_image'] = $dir;
$config['new_image'] = $new;
$config['create_thumb'] = TRUE;
$config['maintain_ratio'] = TRUE;
$config['width'] = 75;
$config['height'] = 50;

$this->load->library('image_lib', $config);

$this->image_lib->resize();

redirect('home','location');

thanks for your help