Zydas 1211 chipset with zd1211 driver throws a 'SIOCSIFFLAGS : No such file or directory' error in ifconfig <interface> up.
Or an error similar to this in dmesg:
usb 1-1: Could not load firmware file zd1211/zd1211b_ub. Error number -2
zd1211rw 1-1:1.0: couldn't load firmware. Error number -2.
This, according to aircrack-ng wiki, means that firmware is missing.
You should download it from here and put the folder named zd1211 in your /lib/firmware/zd1211 and/or /lib/firmware/<kernel version from uname -r>/zd1211.
This should fix the issue.