Exceptions running dpsk_loopback example

Hi,

I have just started learning GNU Radio by going through the examples and
so far I’m impressed!

I found the dpsk_loopback example which is close to what I’m trying to
build, but unfortunately it stops with an exception:

Traceback (most recent call last):
File “/tmp/dpsk_loopback.py”, line 153, in
tb = dpsk_loopback()
File “/tmp/dpsk_loopback.py”, line 114, in init
self.connect((self.blks2_packet_decoder_0, 0),
(self.wxgui_scopesink2_0, 0))
File
“/usr/local/lib/python2.7/dist-packages/gnuradio/gr/top_block.py”, line
130, in connect
self._connect(points[i-1], points[i])
File
“/usr/local/lib/python2.7/dist-packages/gnuradio/gr/top_block.py”, line
142, in _connect
dst_block.to_basic_block(), dst_port)
File
“/usr/local/lib/python2.7/dist-packages/gnuradio/gr/runtime_swig.py”,
line 4328, in primitive_connect
return _runtime_swig.top_block_sptr_primitive_connect(self, *args)
ValueError: itemsize mismatch: ofdm_mod0:0 using 1, scope_sink0:0 using
4

It would be great if anyone has a suggestion on what is going wrong
here.

My environment is a self compiled (build-gnuradio) GNU Radio 3.7.2.1
running on Ubuntu 13.10 64bit.

Thanks!
-Erich