First-time backup GPG Usage Error

This is the command I ran:

duplicity full --use-agent --hidden-encrypt-key "$ENC_KEY_1" --hidden-encrypt-key "$ENC_KEY_2" --gpg-options "compress-algo=bzip2 z=9" --name $BACKUP_NAME --sign-key $SIGN_KEY --volsize 128 /home/kevin file:///run/media/kevin/backup/home

I'm not actually using those variables, I just put them there for privacy.

I recieve the following traceback:

GPG error detail: Traceback (most recent call last):
  File "/usr/bin/duplicity", line 1411, in <module>
    with_tempdir(main)
  File "/usr/bin/duplicity", line 1404, in with_tempdir
    fn()
  File "/usr/bin/duplicity", line 1374, in main
    full_backup(col_stats)
  File "/usr/bin/duplicity", line 509, in full_backup
    globals.backend)
  File "/usr/bin/duplicity", line 386, in write_multivol
    globals.gpg_profile, globals.volsize)
  File "/usr/lib/python2.7/site-packages/duplicity/gpg.py", line 335, in GPGWriteFile
    file.write(data)
  File "/usr/lib/python2.7/site-packages/duplicity/gpg.py", line 197, in write
    self.gpg_failed()
  File "/usr/lib/python2.7/site-packages/duplicity/gpg.py", line 218, in gpg_failed
    raise GPGError, msg
GPGError: GPG Failed, see log below:
===== Begin GnuPG log =====
usage: gpg [options] [filename]
===== End GnuPG log =====

I am running Arch Linux, with repo versions of GPG (2.0.20) and Duplicity (0.6.21)

I was having tons of trouble before with the multiple keys-- I'm asked for one password instead of two.
However, once I got gpg-agent up and running, this problem came up, and now I'm stuck.