Duplicity restore produces an error "No backup chains found"

I'm testing duplicity's restore functionality:

duplicity restore file://fullSystemBackup/ backupOutput

Which produces an error of:

Local and Remote metadata are synchronized, no sync needed.
Last full backup date: none
GnuPG passphrase for decryption: 
Traceback (most recent call last):
  File "/usr/bin/duplicity", line 1546, in <module>
    with_tempdir(main)
  File "/usr/bin/duplicity", line 1540, in with_tempdir
    fn()
  File "/usr/bin/duplicity", line 1391, in main
    do_backup(action)
  File "/usr/bin/duplicity", line 1468, in do_backup
    restore(col_stats)
  File "/usr/bin/duplicity", line 731, in restore
    restore_get_patched_rop_iter(col_stats)):
  File "/usr/bin/duplicity", line 753, in restore_get_patched_rop_iter
    backup_chain = col_stats.get_backup_chain_at_time(time)
  File "/usr/lib/python2.7/dist-packages/duplicity/collections.py", line 971, in get_backup_chain_at_time
    raise CollectionsError("No backup chains found")
CollectionsError: No backup chains found

What does this error mean?

The path in file://fullSystemBackup/ should be an absolute path...

So I did file://"$PWD"/fullSystemBackup/...