Cannot run Wikipedia Lens tutorial

I follow this tutorial to learn basic knowledge about how to create a unity lens: http://developer.ubuntu.com/2012/04/how-to-create-a-wikipedia-unity-lens-for-ubuntu/

But at the step to launch the lens, we got the same output from this bug(https://bugs.launchpad.net/singlet/+bug/1000669)...:
(process:4531): libunity-WARNING **: unity-scope-factory.vala:78: Unable to search for scopes: No such file or directory
WARN 2013-08-28 15:34:47 unity.glib.dbus.proxy GLibDBusProxy.cpp:418 Calling method "Search" on object path: "/unity/singlet/lens/wikipedia" failed: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name unity.singlet.lens.wikipedia was not provided by any .service files
WARN 2013-08-28 15:34:47 unity.glib.dbus.proxy GLibDBusProxy.cpp:418 Calling method "Search" on object path: "/unity/singlet/lens/wikipedia" failed: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name unity.singlet.lens.wikipedia was not provided by any .service files
WARN 2013-08-28 15:34:50 unity.glib.dbus.proxy GLibDBusProxy.cpp:418 Calling method "Search" on object path: "/unity/singlet/lens/wikipedia" failed: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name unity.singlet.lens.wikipedia was not provided by any .service files

The last error line is important I think, it tells that the Wikipedia Lens was not registered..

Someone can help me?