You most likely have an aircrack-ng version that already implements the PTW crack mode by default, therefore the –z switch is not needed.aircrack-ng -z -b 00:14:6C:7E:40:80 output*.cap
How long is your WEP key? If you do not specify the bit length (using the –n switch) aircrack-ng will assume the most commonly used 128 bit key length, and also automatically try 10 000 64 bit keys for you. You should also check that you have gathered enough weak ivs to actually be able to crack the key.and it took 10 minutes and hadn't come up with anything so i gave up on that one for now. Any ideas?