Howto module segmentation fault

Hello, I recently got python programs to successfully import the howto
module, but I cannot use the functions. Any help or suggestions would be
greatly appreciated:

Python code:
#!/usr/bin/env python

from gnuradio import gr
import howto

class my_top_block(gr.top_block):

def init(self):
gr.top_block.init(self)

src_nums = (4, 5, 6)
src = gr.vector_source_f (src_nums)
sqr = howto.square_ff ()
dst = gr.vector_sink_f ()
self.connect (src, sqr)
self.connect (sqr, dst)
print "src: ", src
print "sqr: ", sqr
print "dst.data: ", dst.data()

if name == ‘main’:
my_top_block().run()

Output:
src: <gr_block vector_source_f (1)>
sqr: <gr_block square_ff (2)>
dst.data: ()
Segmentation fault

Thanks,
Mike