According to the following installation methods:
http://blog.sina.com.cn/s/blog_140c4cf3d0102wm0o.html
After running opencv demo (facedetect) problems are as follows:

The Exception has occurred: TypeError
OpenCV returned NULL
The File "D: \ Downloads, opencv - 2.4.13, opencv, sources \ samples \ python \ facedetect py", line 63, in & lt; module>
Cascade=CV. The Load (options. Cascade)

Excuse me what reason is this?