LatestNewsPlugin not work

[dukelec]

During plugin edit phase, server return the 500 error, log:

response_add....... Latest News Entries
escapejs: value:5 class:<class 'aldryn_news.models.LatestNewsPlugin'>
[13/Jan/2015 21:50:30] "POST /en/admin/cms/page/edit-plugin/3/ HTTP/1.1" 500 260963
[13/Jan/2015 21:50:30] "GET /en/admin/cms/page/resolve/?model=cms.page&pk=1 HTTP/1.1" 200 4

Traceback:

Environment:


Request Method: POST
Request URL: http://localhost:8000/en/admin/cms/page/edit-plugin/11/

Django Version: 1.6.9
Python Version: 2.7.6
Installed Applications:
('djangocms_admin_style',
 'djangocms_text_ckeditor',
 'django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.admin',
 'django.contrib.sites',
 'django.contrib.sitemaps',
 'django.contrib.staticfiles',
 'django.contrib.messages',
 'cms',
 'mptt',
 'menus',
 'sekizai',
 'djangocms_style',
 'djangocms_column',
 'filer',
 'easy_thumbnails',
 'taggit',
 'aldryn_news',
 'hvad',
 'django_select2',
 'cmsplugin_filer_image',
 'cmsplugin_filer_file',
 'cmsplugin_filer_folder',
 'cmsplugin_filer_link',
 'cmsplugin_filer_teaser',
 'cmsplugin_filer_utils',
 'cmsplugin_filer_video',
 'djangocms_flash',
 'djangocms_googlemap',
 'djangocms_inherit',
 'south',
 'reversion',
 'ingenic_cms')
Installed Middleware:
('django.contrib.sessions.middleware.SessionMiddleware',
 'django.middleware.csrf.CsrfViewMiddleware',
 'django.contrib.auth.middleware.AuthenticationMiddleware',
 'django.contrib.messages.middleware.MessageMiddleware',
 'django.middleware.locale.LocaleMiddleware',
 'django.middleware.doc.XViewMiddleware',
 'django.middleware.common.CommonMiddleware',
 'django.middleware.clickjacking.XFrameOptionsMiddleware',
 'cms.middleware.user.CurrentUserMiddleware',
 'cms.middleware.page.CurrentPageMiddleware',
 'cms.middleware.toolbar.ToolbarMiddleware',
 'cms.middleware.language.LanguageCookieMiddleware')


Traceback:
File "/home/duke/Desktop/ingenic_cms/env/lib/python2.7/site-packages/django/core/handlers/base.py" in get_response
  112.                     response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/home/duke/Desktop/ingenic_cms/env/lib/python2.7/site-packages/django/utils/decorators.py" in _wrapped_view
  99.                     response = view_func(request, *args, **kwargs)
File "/home/duke/Desktop/ingenic_cms/env/lib/python2.7/site-packages/django/views/decorators/cache.py" in _wrapped_view_func
  52.         response = view_func(request, *args, **kwargs)
File "/home/duke/Desktop/ingenic_cms/env/lib/python2.7/site-packages/django/contrib/admin/sites.py" in inner
  198.             return view(request, *args, **kwargs)
File "/home/duke/Desktop/ingenic_cms/env/lib/python2.7/site-packages/cms/admin/pageadmin.py" in edit_plugin
  1491.             return super(PageAdmin, self).edit_plugin(*args, **kwargs)
File "/home/duke/Desktop/ingenic_cms/env/lib/python2.7/site-packages/django/views/decorators/clickjacking.py" in wrapped_view
  41.         resp = view_func(*args, **kwargs)
File "/home/duke/Desktop/ingenic_cms/env/lib/python2.7/site-packages/cms/admin/placeholderadmin.py" in edit_plugin
  392.             response = plugin_admin.add_view(request)
File "/home/duke/Desktop/ingenic_cms/env/lib/python2.7/site-packages/django/utils/decorators.py" in _wrapper
  29.             return bound_func(*args, **kwargs)
File "/home/duke/Desktop/ingenic_cms/env/lib/python2.7/site-packages/django/utils/decorators.py" in _wrapped_view
  99.                     response = view_func(request, *args, **kwargs)
File "/home/duke/Desktop/ingenic_cms/env/lib/python2.7/site-packages/django/utils/decorators.py" in bound_func
  25.                 return func(self, *args2, **kwargs2)
File "/home/duke/Desktop/ingenic_cms/env/lib/python2.7/site-packages/django/db/transaction.py" in inner
  371.                 return func(*args, **kwargs)
File "/home/duke/Desktop/ingenic_cms/env/lib/python2.7/site-packages/django/contrib/admin/options.py" in add_view
  1167.                 return self.response_add(request, new_object)
File "/home/duke/Desktop/ingenic_cms/env/lib/python2.7/site-packages/cms/plugin_base.py" in response_add
  238.         return super(CMSPluginBase, self).response_add(request, obj, **kwargs)
File "/home/duke/Desktop/ingenic_cms/env/lib/python2.7/site-packages/django/contrib/admin/options.py" in response_add
  963.                 'obj': escapejs(obj)
File "/home/duke/Desktop/ingenic_cms/env/lib/python2.7/site-packages/django/utils/functional.py" in wrapper
  203.             return func(*args, **kwargs)
File "/home/duke/Desktop/ingenic_cms/env/lib/python2.7/site-packages/django/utils/html.py" in escapejs
  61.     return mark_safe(force_text(value).translate(_js_escapes))

Exception Type: TypeError at /en/admin/cms/page/edit-plugin/11/
Exception Value: expected a character buffer object

I have fixed this by remove the __unicode__ function in the LatestNewsPlugin class.