Filtering by dates in Google App Engine's Datastore

Question

I'm having some issues trying to filter a set of objets by their date. Right now I can get all of a user's transactions like this:

> t = Transaction.all().filter("client_email =", "some_email").filter("application_id =", "foo").fetch(100)
> len(t)
# => 4

Now, if I want to set up some date filters:

> min = datetime.datetime(2009, 2, 3, 0, 0)
> max = datetime.datetime(2009, 11, 4, 0, 0)

> len(Transaction.gql("WHERE client_email =:1 AND date >:2 AND date <=:3 AND application_id =:4", 
                      "some_email", min, max, "foo").fetch(100))
# => 2

I know all those transactions have a date < max && > min:

> map(lambda x: x.date, t)
# => [datetime.datetime(2009, 10, 2, 22, 43, 51), datetime.datetime(2009, 10, 5, 2, 5, 24), datetime.datetime(2009, 10, 7, 16, 51, 5), datetime.datetime(2009, 10, 7, 16, 6, 53)]

Yup, all those transactions were made in October 2009. I filtered them in Python just to confirm that it was right:

> trans = filter(lambda x: x.date < max and x.date >= min, t)
> len(trans)
# => 4

So yes, they all have the correct dates but due to something in my query the results don't match the expected results, any idea of what might be wrong in the query?