"The use statement with non-compound name...."

Question

Good Days, I have a problem with my code

use \Crypto; 
class Server extends Model {
function __construct() {
    parent::__construct('server');
}

function SetPass($text) {
    $key = \Base::instance()->get('APP_KEY');
    $crypt = new \Helper\Crypt($key);
    $this->set('root_pass',$crypt->encrypt($text));
    return $this;
}

function GetPass() {
    $key = \Base::instance()->get('APP_KEY');
    $crypt = new \Helper\Crypt($key);
    $text = $this->get('root_pass');
    return $crypt->decrypt($text);
}
}

Can anyone help me ? because the code get:

PHP Warning: The use statement with non-compound name 'Crypto' has no effect in /home/trik1725/public_html/3netis/panel/model/server.php on line 3