My breakpoints are ignored (simple app engine project)

I'm brand new to PyCharm, having just downloaded it today.  I created a simple app engine project, and copied the "appengine" sample from Google's sample (https://code.google.com/p/google-api-python-client/source/browse/#hg%2Fsamples%2Fappengine).  I got the sample to run, but then wanted to look inside.  I tried setting breakpoints in the get methods of the two xxxHandler classes.  But the breakpoints are never hit.

At first I thought it might be because both methods have decorators, but I added a third handler that doesn't use a decorator, and its breakpoint isn't hit, either.

I assume I'm missing something really obvious here.  Any ideas?