Update rssi fails/ rssi example

[ElesGergo]

I am developing a ble software for rpi3 and I need to see the updated rssi on the pheripheral.
What I want to achive is to only let devices connect (or let them connect and disconnect them if they are too far) under a cetain rssi(-50 can connect, -60 can't).
I tried to implement the
bleno.updateRssi((rssi,err)=>{ console.log(rssi) });
function and subscribe to the
bleno.on("rssiUpdate",(rssi,err)=>{console.log(rssi)})
but it does not seemed to log anything work.
Can you help me out with an example?