Forum: GNU Radio constellation problem

i had created qpsk demod by using mpsk receiver (m=4) making some
modifies and than it gives
me error like below? any help?

Traceback (most recent call last):
  File "/home/bynkln/Desktop/deneme/final
Report/grcMpskRx/top_block.py", line 183, in <module>
    tb = top_block()
  File "/home/bynkln/Desktop/deneme/final
Report/grcMpskRx/top_block.py", line 98, in __init__
    self.digital_constellation_decoder_cb_0_3 =
digital.constellation_decoder_cb(digital.constellation_qpsk())
  File
"/usr/local/lib/python2.7/dist-packages/gnuradio/digital/digital_swig.py",
line 3910, in constellation_decoder_cb
    return _digital_swig.constellation_decoder_cb(*args, **kwargs)
TypeError: in method 'constellation_decoder_cb', argument 1 of type
'digital_constellation_sptr'