Im still having trouble with this USB wlan card

iwconfig shows:
wlan0 unassociated Nickname: "rtl_wifi"
Mode:Managed Access Point: Not-Associated Sensitivity: 0/0

even when i try
sudo ifdown wlan0

i get :
ifdown: interface wlan0 not configured.

iwconfig wlan0 mode monitor
gives me:
Error for wireless request "Set Mode" (8B06) :
SET failed on device wlan0 ; Invalid argument.
sudo iwconfig wlan0 mode monitor.

im still a newb but im trying to learn about this issue.
but i need help understanding why my card is not working on aircrack-ng on Kali-Linux i though it should work straight out of the box on kali-linux without and configuring. although it looks lie this is not the case.

what do i need to do to get my usb wlan card to work in monitor mode ?