i want to encrypt my full HDD using win 8.1 pro and bitlocker using a password to authenticate at boot.i have managed to encrypt successfully using a PIN (the only option that seems available). please see screenshot,"group policy"where it mentions the use of a password but i've tried a few different ways with no luck. i've also included a screenshot of the TPM,in case its related to that. i think that to encrypt using a password for boot authentication one has to not use TPM.

please advise.

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