Error occured at install

[rkyymmt]

==> python -c import setuptools... --no-user-cfg install --prefix=/usr/local/Cellar/chainer/1.0.0/libexec/vendor --single-version-externally-managed --record=installed.txt
  File "setup.py", line 88, in main
    conf["CUDA_INC_DIR"] = [join(conf["CUDA_ROOT"], "include")]
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/posixpath.py", line 70, in join
    elif path == '' or path.endswith('/'):
AttributeError: 'NoneType' object has no attribute 'endswith'