Not reading rssi Holybro Pix4

Hello.
I moved to frsky from flysky transmitter with my holybro pixhawk 4.
Tried to connect the rssi analog signal from xsr (a pad near antena) to rssi pin in SBUS IN, pin 3 on pix, documentation says that its rssi pin.
Set all parameters from rssi guide.
RSSI_TYPE=1
RSSI_ANA_PIN = 103
volt from 0 to 3.3.
But rssi always at 0. checked with voltmeter the pad, getting about 3 - 3.1v.
Anything I missed?
rssi from channel is working ok.
Thanks!