Entity Framework Include () не работает

I have the following EF query:

TestEntities db = new TestEntities();
var questions = from q in db.Questions.Include("QuestionType")
                from sq in db.SurveyQuestions
                where sq.Survey == surveyTypeID
                orderby sq.Order
                select q;

foreach( var question in questions ) {
    // ERROR: Null Reference Exception
    Console.WriteLine("Question Type: " + question.QuestionType.Description);
}

I am getting a null reference exception when I access the QuestionType property. I am using Include("QuestionType") but it doesn't appear to be working. What am I doing wrong?

Edit: It does not throw a null reference exception when I have Lazy Loading turned on.

Edit: Include() seems to be working when i do the following:

var questions = db.Questions.Include("QuestionType").Select(q => q);

When I predicate on a separate entity Include seems to fail. Is that not allowed when using Include? What about my query is causing this thing to not work?