Gateway receives, but not send?

[martjah]

Hello,

I have a Mysensors Gateway connected to my Raspberry Pi with Domoticz.
I've made the "secret knock sensor" and i use it as a clap on/clap off sensor for my living room lamp.
If i put my device under the couch, i cannot turn it on/off with Domoticz. When i turn of the lamp with clapping, Domoticz updates with the latest status.
When i move the sensor on the living room table, it will turn on/off using Domoticz.

The gateway has an antenna and the sensor does not. I always assumed that when its strong enough to receive the signal, it can also send it...... Can someone explain why it is not working?