What is the error in this multicast message sending loop?

MulticastSocket socket = new MulticastSocket();
InetAddress group = InetAddress.getByName("225.0.0.1");
socket.joinGroup(group);
for (int i = 0; i < 5; i++) {
    String message = "Message " + i;
    byte[] buf = message.getBytes();
    DatagramPacket packet = new DatagramPacket(buf, buf.length, group, 5000);
    socket.send(packet);
}
socket.leaveGroup(group);
socket.close();