Set Failed on device wlan

For some wireless adapters, we can set the monitor mode, in order to capture all the headers information and transmission by others over the air.

According to wireshark wiki, the following command is used in linux:
sudo iwconfig wlan1 mode monitor

But I kept receive the error message "set Failed on device wlan1".

Finally, I found that I need turn the device off first by
sudo ifconfig wlan1 down
sudo iwconfig wlan1 mode monitor
sudo ifconfig wlan1 up.

Then it rocks as you want now :)