Trying to import a .nif into Blender, for Oblivion mod work, I get the following error:

Blender NIF Scripts 2.5.5 (running on Blender 249, PyFFI 2.1.6)
pyffi.toaster:INFO:--- fix_mergeskeletonroots ---
pyffi.toaster:INFO:  ~~~ NiNode [Scene Root] ~~~
pyffi.toaster:INFO:--- fix_sendgeometriestobindposition ---
pyffi.toaster:INFO:  ~~~ NiNode [Scene Root] ~~~
pyffi.toaster:INFO:    sending geometries to bind position
Traceback (most recent call last):
  File "C:\Program Files (x86)\Blender Foundation\Blender\.blender\scripts\bpymo
dules\nif_common.py", line 1227, in gui_button_event
    self.gui_exit()
  File "C:\Program Files (x86)\Blender Foundation\Blender\.blender\scripts\bpymo
dules\nif_common.py", line 1579, in gui_exit
    self.callback(**self.config)
  File "C:\Program Files (x86)\Blender Foundation\Blender\.blender\scripts\impor
t\import_nif.py", line 3750, in config_callback
    importer = NifImport(**config)
  File "C:\Program Files (x86)\Blender Foundation\Blender\.blender\scripts\impor
t\import_nif.py", line 274, in __init__
    self.import_root(root)
  File "C:\Program Files (x86)\Blender Foundation\Blender\.blender\scripts\impor
t\import_nif.py", line 309, in import_root
    pyffi.spells.nif.fix.SpellSendGeometriesToBindPosition(data=data).recurse()
  File "C:\Python26\lib\site-packages\pyffi\spells\__init__.py", line 289, in re
curse
    self.recurse(child)
  File "C:\Python26\lib\site-packages\pyffi\spells\__init__.py", line 298, in re
curse
    if self.branchentry(branch):
  File "C:\Python26\lib\site-packages\pyffi\spells\nif\__init__.py", line 135, i
n branchentry
    self.skelrootentry(branch)
  File "C:\Python26\lib\site-packages\pyffi\spells\nif\fix.py", line 380, in ske
lrootentry
    branch.send_geometries_to_bind_position()
  File "C:\Python26\lib\site-packages\pyffi\formats\nif\__init__.py", line 5106,
 in send_geometries_to_bind_position
    if bonenode.name in bone_bind_transform:
AttributeError: 'NoneType' object has no attribute 'name'