Cannot stream raw udp from VLC to another VLC on same machine

DETAIL: VLC runs correctly "as if" it was streaming, but in fact NOTHING ON THE NETWORKS.

REPRODUCE: EASY, Just run vlc -vvv "http://ouifm.ice.infomaniak.com/ouifm-high.mp3" --sout #transcode{vcodec=none,acodec=s16l,ab=128,channels=2,samplerate=48000}:standard{access=udp,mux=raw,dst=127.0.0.1:3001} AND OTHER VLC for listening.

It seems that nothing is also sent on the network, using other ip than 127.0.0.1 ....

Thanks for your support.