Cannot open update manager

[Shashank Sonthalia]

Distribution: Ubuntu 10.10 maverick
Application: Ubuntu Tweak 0.5.8
Desktop: gnome

Traceback (most recent call last):
  File "/usr/lib/python2.6/dist-packages/ubuntutweak/mainwindow.py", line 425, in setup_notebook
    page = module()
  File "/usr/lib/python2.6/dist-packages/ubuntutweak/modules/updatemanager.py", line 44, in __init__
    self.update_list()
  File "/usr/lib/python2.6/dist-packages/ubuntutweak/modules/updatemanager.py", line 59, in update_list
    PACKAGE_WORKER.update_apt_cache(init=True)
  File "/usr/lib/python2.6/dist-packages/ubuntutweak/common/package.py", line 216, in update_apt_cache
    self.cache = apt.Cache()
  File "/usr/lib/python2.6/dist-packages/apt/cache.py", line 88, in __init__
    self.open(progress)
  File "/usr/lib/python2.6/dist-packages/apt/cache.py", line 130, in open
    self._list.read_main_list()
SystemError: E:Type '“deb' is not known on line 61 in source list /etc/apt/sources.list