Mvc-infinite-scroll package null session

Question

I am trying to implement this pakage

After I load the data from the DB, I store it like this:

Session["reservations"] = futureReservations.ToDictionary(x => custIndex++, x => x);

Then I am trying to get only the data I need for the current page:

public Dictionary<int, Restaurants> GetRecordsForPage(int pageNum)
        {
            Dictionary<int, Restaurants> reservations = (Session["reservations"] as Dictionary<int, Restaurants>);

            int from = (pageNum * RecordsPerPage);
            int to = from + RecordsPerPage;


            return reservations
                .Where(x => x.Key > from && x.Key <= to)
                .ToDictionary(x => x.Key, x => x.Value);
        }

The problem is that the reservations variable stays null, even if the session info is correct. Can anyone help me figure out why?