harvesting error

[daimajia]

[E 140101 23:45:19 websocket:306] Uncaught exception in /harvesting
Traceback (most recent call last):
File "/usr/local/lib/python2.7/dist-packages/tornado/websocket.py", line 303, in wrapper
return callback(_args, *_kwargs)
File "server.py", line 55, in on_message
self.process(image)
File "server.py", line 94, in process
result = opencv.Image(label=label).persist(cv_image)
File "/root/School/Face/face-recognition-server-master/opencv.py", line 159, in persist
cropped = to_grayscale(crop_faces(cv_image, faces))
File "/root/School/Face/face-recognition-server-master/opencv.py", line 41, in crop_faces
return img[y:y+h,x:x+w]
File "/usr/local/lib/python2.7/dist-packages/PIL/Image.py", line 512, in getattr
raise AttributeError(name)
AttributeError: getitem

[daimajia]

when try to saving the first image, trigger this error.