Error somewhere in the tutorial

[mittenchops]

So, first off, awesome tutorial, and thanks for making it!

But there seems to be an error somewhere, and I am having trouble pegging it. It's somewhere between the section ending just before this one:
http://docs.mongodb.org/manual/tutorial/write-a-tumblelog-application-with-flask-mongoengine/#configure-mongoengine-and-flask

and the end of this one:
http://docs.mongodb.org/manual/tutorial/write-a-tumblelog-application-with-flask-mongoengine/#add-templates

I can successfully run:
python manage.py runserver

at the first point, but not at the second.

I posted question on SO, and the commenters also remembered having to change a couple things to get it to work:
http://stackoverflow.com/questions/16799231/replicating-flask-mongodb-gets-internal-server-error

I am not so clever as they were to figure out what.

[mittenchops]

Some candidates:

Tutorial has:
class Post(db.Document):
versus github has
class Post(db.DynamicDocument):