i have downloaded everything i need to import/export nif scripts, but neither options are working. below are the programs i downloaded and the error messages:

programs:
python 2.5.2
pyffi
blender nif scripts
nifskope
downgraded blender to 2.48 (WAS 2.49)

Error Messages:
import: AttributeError: 'NiTriShape' object has no attribute isSkin
export: AttributeError: 'Matrix44' object has no attribute 'setIdentity'

both are on default settings. import is a morrowind helm mesh (have tried multiple meshes with the same results) and export is a simple cube

help will be greatly appreciated ^_^