websocket write not working as I expected

[aaddame]

I have the following situation:

On my android device I have a push button connected to V0. On my particle photon I have a 433Mhz transmitter to control my lights.
BLYNK_WRITE(V0) {
Blynk.notify("v0 msg");
transmitter.sendGroup(param.asInt());
}

When I push the button, the label changes to on and my lights turn on.
Doing the same with Blynk write node doesn't work.
I can see in the blynk server log that pushing the button generates 1vw01
From node-red I see vw01