Invalid label name ? #52

Traceback (most recent call last):
  File "/home/pazz/projects/gmailieer/gmi", line 8, in <module>
    g.main ()
  File "/home/pazz/projects/gmailieer/lieer/gmailieer.py", line 143, in main
    args.func (args)
  File "/home/pazz/projects/gmailieer/lieer/gmailieer.py", line 193, in sync
    self.push (args, True)
  File "/home/pazz/projects/gmailieer/lieer/gmailieer.py", line 245, in push
    actions.append (self.remote.update (rm, nm, self.local.state.last_historyId, self.force))
  File "/home/pazz/projects/gmailieer/lieer/remote.py", line 109, in func_wrap
    return func (self, *args, **kwargs)
  File "/home/pazz/projects/gmailieer/lieer/remote.py", line 503, in update
    return self.__push_tags__ (gid, add, rem)
  File "/home/pazz/projects/gmailieer/lieer/remote.py", line 109, in func_wrap
    return func (self, *args, **kwargs)
  File "/home/pazz/projects/gmailieer/lieer/remote.py", line 519, in __push_tags__
    (lid, ll) = self.__create_label__ (a)
  File "/home/pazz/projects/gmailieer/lieer/remote.py", line 109, in func_wrap
    return func (self, *args, **kwargs)
  File "/home/pazz/projects/gmailieer/lieer/remote.py", line 630, in __create_label__
    lr = self.service.users ().labels ().create (userId = self.account, body = label).execute ()
  File "/usr/lib/python3/dist-packages/oauth2client/_helpers.py", line 133, in positional_wrapper
    return wrapped(*args, **kwargs)
  File "/usr/lib/python3/dist-packages/googleapiclient/http.py", line 838, in execute
    raise HttpError(resp, content, uri=self.uri)
googleapiclient.errors.HttpError: <HttpError 400 when requesting https://www.googleapis.com/gmail/v1/users/octo%40gmail.com/labels?alt=json returned "Invalid label name">