duply and webdav

i am trying to run duply to backup my vps to a webdav storage server.
in the conf i see this:
webdav[s]://user[:password]@other.host/some_dir

so i use this: TARGET='webdav://myname:[email protected]/backups_linux/vps2'

but i get this error:

Using installed duplicity version 0.6.18, python 2.7.3, gpg 1.4.12 (Home: ~/.gnupg), awk 'GNU Awk 4.0.1', bash '4.2.37(1)-release (i486-pc-linux-gnu)'.

Test - En/Decryption skipped. (GPG disabled)

--- Start running command PRE at 08:37:37.151 ---
Skipping n/a script '/root/.duply/backupvps2/pre'.
--- Finished state OK at 08:37:37.163 - Runtime 00:00:00.011 ---

--- Start running command BKP at 08:37:37.174 ---
Import of duplicity.backends.giobackend Failed: No module named gio
Reading globbing filelist /root/.duply/backupvps2/exclude
Traceback (most recent call last):
File "/usr/bin/duplicity", line 1404, in
with_tempdir(main)
File "/usr/bin/duplicity", line 1397, in with_tempdir
fn()
File "/usr/bin/duplicity", line 1273, in main
sync_archive(decrypt)
File "/usr/bin/duplicity", line 1025, in sync_archive
remlist = globals.backend.list()
File "/usr/lib/python2.7/dist-packages/duplicity/backends/webdavbackend.py", line 182, in list
log.Info("%s" % (document,))
UnboundLocalError: local variable 'document' referenced before assignment

08:37:39.828 Task 'BKP' failed with exit code '30'.
--- Finished state FAILED 'code 30' at 08:37:39.828 - Runtime 00:00:02.654 ---

--- Start running command POST at 08:37:39.845 ---
Skipping n/a script '/root/.duply/backupvps2/post'.
--- Finished state OK at 08:37:39.856 - Runtime 00:00:00.011 ---
root@vps:/tmp#

i tried to mount the webdav into my vps, but fuse i snot installed on my vps