SINR doesn’t appeared even in monitor mode

Hi everyone. I'm currently try to sniff a WiFi SINR value using TCPDump. I put my adapter on monitor mode already but when i try to capture any traffic. Nothing is captured. Can anyone give me a solution?

[[email protected] ~]# iwconfig lo no wireless extensions.

eth0 no wireless extensions.

wifi0 no wireless extensions.

pan0 no wireless extensions.

ath0 IEEE 802.11g ESSID:"" Nickname:"" Mode:Monitor Channel:0 Access Point: Not-Associated Bit Rate:0 kb/s Tx-Power:18 dBm Sensitivity=1/1 Retry:off RTS thr:off Fragment thr:off Encryption key:off Power Management:off Link Quality=0/70 Signal level=-98 dBm Noise level=-98 dBm Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0 Tx excessive retries:0 Invalid misc:0 Missed beacon:0

[[email protected] ~]# tcpdump -i ath0 -s 0 -w stress.pcap tcpdump: bind: Network is down