bitlocker command to unlock drive doesn't work

hi friends

i encrypted a data volume (E:) via bitlocker & i saved the recovery key file (for example saved as F:\file.txt) on another drive.

now i want to unlock that drive with this recovery file via command line , but the following commands which are based on manage-bde help examples (manage-bde /?) don't work :

manage-bde -unlock E: -recoverykey f:\file.txt

also i ranamed that text file which contains recovery key from file.txt to file.bek & then ran the following command , but again doesn't work:

manage-bde -unlock E: -recoverykey f:\file.bek

what is the cause?

thanks in advance