I had busybox installed too and got that error. I used busybox pro and updated to the newest version and it worked. Don't think that since you already have it installed that that is enough, reinstall it and make sure it is updated.
Sent from my SGH-T959V using xda premium
I did as you said prior to actually reading it thinking maybe it needed to be updated. still get no unlock code. like I said before though, it could be because my device is already unlocked.
Sent from within pure darkness.