imshow misunderstanding ?

edit

"2.bmp" is a valid bitmap file located in the correct folder. So what's wrong with the following code to make it produce the error ...

error: ........\opencv\modules\highgui\src\window.cpp:261: error: (-215) size.width>0 && size.height>0 in function cv::imshow

import cv2

ifile = cv2.imread("C:\Users\ericnei\My Work\2.bmp")  
cv2.imshow("Demo",ifile)
cv2.waitKey(0)
cv2.destroyAllWindows()