Attribute key error

I have installed Gnuradio-3.1.3 on Red Hat Enterprise Linux-4.The
installation of gnuradio was successful.Even I have got USRP connected
and have loaded the firmware.

But when I try to run the given examples of “gr-utils” for example i get the following error:-

[root@localhost python]# ./ Traceback (most recent call

File “./”, line 23, in ?

from gnuradio import gr, gru

File “/usr/lib/python2.3/site-packages/gnuradio/gru/”, line 37,
in ?

exec “from gnuradio.gruimpl.%s import *” % (f,)

File “”, line 1, in ? File
line 28, in ?

import numpy

File “/usr/lib/python2.3/site-packages/numpy/”, line 107, in ?

import ma

File “/usr/lib/python2.3/site-packages/numpy/ma/”, line 14, in ?

import core

File “/usr/lib/python2.3/site-packages/numpy/ma/”, line 114, in ?

max_filler.update([(k,-numpy.inf) for k in [numpy.float32,

AttributeError?: keys

What is the reason for such type of error.Can someone guide me through
this problem.