openshot crash when i'll save my project

hello

I cant save any project..

When i click on "save this project" (enregistrer le projet), openshot dont "crash" but i cant save...

In the terminal :

NEW SDL CONSUMER
Traceback (most recent call last):
  File "/usr/lib/pymodules/python2.7/openshot/windows/NewProject.py", line 200, in on_btnCreateProject_clicked
    self.create_project()
  File "/usr/lib/pymodules/python2.7/openshot/windows/NewProject.py", line 240, in create_project
    self.project.Save("%s/%s.osp" % (localFolder, localName))
  File "/usr/lib/pymodules/python2.7/openshot/classes/project.py", line 339, in Save
    save_project.save_project(self, file_path)
  File "/usr/lib/pymodules/python2.7/openshot/classes/save_project.py", line 31, in save_project
    os.mkdir(os.path.join(project_object.folder, "thumbnail"))
OSError: [Errno 2] Aucun fichier ou dossier de ce type: '/home/username/Desktop/thumbnail'

I'm on ubuntu 13.04 (64 bits) Fresh install
Openshot : 1.4.3 installed with Ubuntu App.. (Logithèque Ubuntu)
Melt : 0.8.8
FFmepg : 6:0.8.6

Thanks for help..