# NameError: name 'TK' is not defined

I reference the following article. http://www.egr.msu.edu/classes/ece480/capstone/spring15/group02/assets/docs/nsappnote.pdf

I have followed article's code, but it appears:

How can i solve this problem?

Did you spell it right? Python is case sensitive and if you are using Tkinter it's spelled Tk().