Struggling with multicast udp send

[Jarrod Roberson]

here is what I am trying, it doesn't work. :-(

send() ->
    {ok, S} = gen_udp:open(5353, [{reuseaddr,
true},{ip,{224,0,0,251}},{broadcast, true}]),
    inet:setopts(S,[{add_membership,{{224,0,0,251},{0,0,0,0}}}]),
    gen_udp:send(S, {224,0,0,251}, 5353, "test").

here is what I get

Erlang R13B02 (erts-5.7.3) [source] [smp:4:4] [rq:4] [async-threads:0]
[kernel-poll:false]

Eshell V5.7.3  (abort with ^G)
1> zcclient:send().
{error,eaddrnotavail}
2>

I know this has to be a simple thing, Programming Erlang has a "broadcast"
udp example that I am trying to make work.
I am not sure that is the same thing as "multicast". Is it?