General :: Cannot Unlock The Password For 'duplicateTest?

I'm experimenting with the passwd command to become more failure it.created an user account that had no password to practice on. I tried using the -u option to unlock it go the response:Cannot unlock the password for 'duplicateTest'!Read the man page and it instructs me to add the -f option to force it to accept unlocking an account with no password but !. I type in:passwd -uf duplicateTestThe response is:passwd: invalid option-- 'f'I rearranging the options and it prompted me to enter a change of finger information. Tried separating them, bracketing them ect...no dice.Can't find anything else on the net but what is stated on the man page, to add the force option.