Artisan: "Command not found"

So I try to add a Command with

php artisan command:make MailSendCommand

The file MailSendCommand.php is created.I edited it to this:

class MailSendCommand extends Command {    protected $name = 'command:send-mail';    protected $description = 'Send mails to the users.';    public function __construct()    {        parent::__construct();    }    public function fire()    {        $this->info('Befehl wird ausgeführt' );    }...

In my file start/artisan.php I added

Artisan::add(new MailSendCommand);

but when I enter 'php artisan command:send-mail' it says:

Command "command:send-mail" is not defined.

It just worked on my Home PC (XAMPP) but not on my live server (PHP 5.5.15 (cgi-fcgi))

'php artisan clear:cache' and 'php artisan dump-autoload' did not help.