Running gnome-screenshot manually produces the same error as above:
[hloeung@darkon ~]$ gnome-screenshot
** WARNING **: Unable to use GNOME Shell's builtin screenshot interface, resorting to fallback X11. Error: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name org.gnome.Shell was not provided by any .service files
Running gnome-screenshot manually produces the same error as above:
[hloeung@darkon ~]$ gnome-screenshot
** WARNING **: Unable to use GNOME Shell's builtin screenshot interface, resorting to fallback X11. Error: GDBus.Error: org.freedesktop .DBus.Error. ServiceUnknown: The name org.gnome.Shell was not provided by any .service files