Problem with ALFA AWUS036NEH on kalI

I bought a new wireless adapter which is alfa awus036neh. When I scan, I can't find any nearby network. But when I put it into monitor mode
ifconfig wlan0 down
airmon-ng check kill
iwconfig wlan0 mode ad-hoc
ifconfig wlan0 up
Then I can see the networks. When i put it back into managed mode and type
iwconfig
i get
wlan0 IEEE 802.11 ESSID:off/any
Mode:Managed Access Point: Not-Associated Tx-Power=20 dBm
Retry short long limit:2 RTS thr:off Fragment thr:off
Encryption key:off
Power Management:off
but still can't see any networks.
When I do
service NetworkManager stop
service NetworkManager restart
service NetworkManager start
I can see the networks for like 30 seconds, and then they're all gone.