I have injection working ok. Get to the stage where airodump-ng is clocking up data packets at an accelerated rate once I run the aireplay-ng -1 -e -b -h & aireplay-ng -3 -a -h commands.

My query is once I get to this stage, the video tutorial suggests that the latter should be run again? Do I just do this straight away?

Also, do I have to stop either of the above before running the aircrack-ng -n 128 -bssid filename.cap command??
In any event, i've tried running aircrack-ng either way and i'm getting an error on the usage of that command.

I am missing something basic here but just can't put my finger on it. If anyone can help, I'd appreciate it.