Can't read erd data

[aashusri]

There is an error related to the conversion factor. Would you happen to know how to fix this?

Traceback (most recent call last):
  File "/home/repo/convert_debug.py", line 122, in <module>
    main()
  File "/home/repo/convert_debug.py", line 80, in main
    data = d.read_data(
  File "/home/repo/wonambi/wonambi/dataset.py", line 395, in read_data
    dat = dataset.return_dat(idx_chan, one_begsam, one_endsam)
  File "/home/repo/wonambi/wonambi/ioeeg/ktlx.py", line 950, in return_dat
    dat_rec = _read_erd(erd_file, begpos_rec, endpos_rec)
  File "/home/repo/wonambi/wonambi/ioeeg/ktlx.py", line 606, in _read_erd
    factor = _calculate_conversion(hdr)
  File "/home/repo/wonambi/wonambi/ioeeg/ktlx.py", line 234, in _calculate_conversion
    raise NotImplementedError('Implement conversion factor for headbox ' +
NotImplementedError: Implement conversion factor for headbox 20