Error on modtool newmod

Hi,

I am relative new to working with gnuradio. When I am running through
the gnuradio out-of-tree module tutorial, I am getting the following
error after
invoking, gr_modtool newmod howto

File “/usr/local/bin/gr_modtool”, line 41, in
main()
File “/usr/local/bin/gr_modtool”, line 36, in main
modtool.setup()
File
“/usr/local/lib/python2.7/dist-packages/gnuradio/modtool/modtool_newmod.py”,
line 70, in setup
self._srcdir = gr.prefs().get_string(‘modtool’, ‘newmod_path’,
options.srcdir)
File
“/usr/local/lib/python2.7/dist-packages/gnuradio/gr/gnuradio_core_general.py”,
line 18953, in get_string
return _gnuradio_core_general.gr_prefs_get_string(self, *args,
**kwargs)
TypeError: in method ‘gr_prefs_get_string’, argument 4 of type
‘std::string const’

I looked in the gr/prefs.py file but do not understand how to fix it.
Any help would be appreciated.

Thanks,
Guannan

I am also facing the same problem. Any help would be appreciated