ValueError: The device has no langid

[smooker]

>>> python import magictpa
Black Magic Trace Extention for GDB (MagicTPA) - 0.1
Copyright (C) 2012  Black Sphere Technologies Ltd.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/home/smooker/.local/share/gdb/python/magictpa/__init__.py", line 35, in <module>
    from magictpa.tpacapture import capture
  File "/home/smooker/.local/share/gdb/python/magictpa/tpacapture.py", line 100, in <module>
    capture = TPACapture(serial, int(ifno, 16), int(epno, 16))
  File "/home/smooker/.local/share/gdb/python/magictpa/tpacapture.py", line 46, in __init__
    custom_match=lambda d: check_serial(d, serial)
  File "/usr/lib/python2.7/dist-packages/usb/core.py", line 1269, in find
    return _interop._next(device_iter(**args))
  File "/usr/lib/python2.7/dist-packages/usb/_interop.py", line 66, in _next
    return next(iter)
  File "/usr/lib/python2.7/dist-packages/usb/core.py", line 1249, in device_iter
    if _interop._all(tests) and (custom_match is None or custom_match(d)):
  File "/home/smooker/.local/share/gdb/python/magictpa/tpacapture.py", line 46, in <lambda>
    custom_match=lambda d: check_serial(d, serial)
  File "/home/smooker/.local/share/gdb/python/magictpa/tpacapture.py", line 37, in check_serial
    s = usb.util.get_string(dev, 8, dev.iSerialNumber)
  File "/usr/lib/python2.7/dist-packages/usb/util.py", line 314, in get_string
    raise ValueError("The device has no langid")
ValueError: The device has no langid
Error while executing Python code.