shortcode not work “Order Time”

Hello,
I would like to use the order time in the email.
I wrote a code for this and inserted it into functions.php:

add_shortcode('order_time_cs', 'shortcode_order_time_cs');	// Shortcode registrieren
function shortcode_order_time_cs() {
	$time = "No Time";
	if ( $order ) {
		$time = $order->get_date_created()->format ('h:i:s'); // Uhrzeit holen
	}
	return $time;
}

In the email template I insert the shortcode with [order_time_cs].
Unfortunately the only output I get is “No Time”

I’m asking for your help.
Many thanks.
Kind regards