OpenCV Error: (-215)size.width>0 && size.height>0 in function imshow

Question

I am trying to make a face tracker that combines Haar Cascade Classification with Lucas Kanade good feature detection. However, I keep getting an error that I cannot figure

Answer 1

cv2.circle and cv2.lines are not working. Mask and frame both are returning None. these functions (line and circle) are in opencv 3 but not in older versions.