Why UBX 160 gain not work (for RX and TX)

[sp h]

Hi, in my USRP x310 I used a daughterboard  ubx160, but in Gnuradio gain is not effect...

gain 0 and gain 100 show the same signal...for FM station it can not show any signal  How can solve my problem?

Gnuardio 3.8.1

UHD 3.15.1

thanks in advance