dmedia-peer-gtk : TypeError: Don't know which D-Bus type to use to encode type "NoneType"

[Angel Guzman Maeso]

Running the binary in source code:

$ ./dmedia-peer-gtk
Traceback (most recent call last):
  File "/dmedia/gtk/peering.py", line 129, in on_get_secret
    self.Dmedia.GetSecret(self.peer_id)
  File "/usr/lib/python3/dist-packages/dbus/proxies.py", line 145, in __call__
    **keywords)
  File "/usr/lib/python3/dist-packages/dbus/connection.py", line 641, in call_blocking
    message.append(signature=signature, *args)
TypeError: Don't know which D-Bus type to use to encode type "NoneType"
Traceback (most recent call last):
  File "/dmedia/gtk/peering.py", line 126, in on_delete_event
    self.Dmedia.Cancel(self.peer_id)
  File "/usr/lib/python3/dist-packages/dbus/proxies.py", line 145, in __call__
    **keywords)
  File "/usr/lib/python3/dist-packages/dbus/connection.py", line 641, in call_blocking
    message.append(signature=signature, *args)
TypeError: Don't know which D-Bus type to use to encode type "NoneType"

ProblemType: Bug
DistroRelease: Ubuntu 13.04
Package: dmedia 13.04.0~bzr600~raring1 [origin: LP-PPA-novacut-daily]
ProcVersionSignature: Ubuntu 3.8.0-13.23-generic 3.8.3
Uname: Linux 3.8.0-13-generic i686
ApportVersion: 2.9.2-0ubuntu5
Architecture: i386
CrashDB: {'impl': 'launchpad', 'project': 'dmedia'}
Date: Tue Apr 2 21:52:53 2013
InstallationDate: Installed on 2013-02-03 (58 days ago)
InstallationMedia: Ubuntu 10.04 LTS "Lucid Lynx" - Release i386 (20100429)
MarkForUpload: True
PackageArchitecture: all
SourcePackage: dmedia
UpgradeStatus: Upgraded to raring on 2013-02-03 (58 days ago)