TypeError: 'NoneType' object is not callable

[isline]

• face_recognition version:1.00
• Python version:3.6
• Operating System:Win7
  dlib version：19.7

Description

Python Report Error：
Traceback (most recent call last):
File "C:/Users/Administrator/PycharmProjects/untitled1/FaceRecognition/1.py", line 12, in
biden_face_encoding = face_recognition.face_encodings(biden_image)[0]
File "D:\Program Files\Python36\lib\site-packages\face_recognition\api.py", line 189, in face_encodings
raw_landmarks = _raw_face_landmarks(face_image, known_face_locations)
File "D:\Program Files\Python36\lib\site-packages\face_recognition\api.py", line 148, in _raw_face_landmarks
face_locations = _raw_face_locations(face_image)
File "D:\Program Files\Python36\lib\site-packages\face_recognition\api.py", line 97, in _raw_face_locations
return face_detector(img, number_of_times_to_upsample)
TypeError: 'NoneType' object is not callable

Function of “face_detector” in api.py is following：
return face_detector(img, number_of_times_to_upsample)

What I Did

i try to run the code follwing:

import face_recognition

biden_image = face_recognition.load_image_file("C:/face/image/z.jpg")
obama_image = face_recognition.load_image_file("C:/face/image/f.jpg")
unknown_image = face_recognition.load_image_file("C:/face/image/z1.jpg")

biden_face_encoding = face_recognition.face_encodings(biden_image)[0]
obama_face_encoding = face_recognition.face_encodings(obama_image)[0]
unknown_face_encoding = face_recognition.face_encodings(unknown_image)[0]

known_faces = [
biden_face_encoding,
obama_face_encoding
]

results = face_recognition.compare_faces(known_faces, unknown_face_encoding)

print("Is the unknown face a picture of Biden? {}".format(results[0]))
print("Is the unknown face a picture of Obama? {}".format(results[1]))
print("Is the unknown face a new person that we've never seen before? {}".format(not True in results))