Please provide a complete example of the failures.  Your report doesn't currently provide enough information to reproduce the reported issue.

If the reported error message is accurate, it looks at first glance like the error message at least could use some improvement, since (at least as a non-tkinter user) I have no idea what it would mean for Tk() to be defined, since it isn't a Python identifier.  On the other hand, if that error message comes from Tk itself and not Python, then it is probably correct.