Unable to POST from backbone to express

Here is the view i am working on. It is a simple registration form. It captures data from a group of input tags, and posts it to the server. The POST data does not seem to be making it to the server however.

define(['text!templates/register.html'], function(registerTemplate){
    var registerView = Backbone.View.extend({
        el: $('#content'),

        events: {
            "submit form" : "register"
        },

        register: function() {

            var postData = {
                firstname: $('input[name=firstname]').val(),
                lastname: $('input[name=lastname]').val(),
                email: $('input[name=email]').val(),
                password: $('input[name=password]').val()
            };

            $.post('/register', postData, function(data){
                console.log(data);
                }
            }).error(function(err){
                console.log(err);
            });

            return false;
        },

        render: function(){
            this.$el.html(registerTemplate);
        }
    });
        return registerView;
});

Here is the request listener in my app. All the variables show 'undefined' when logged.

app.post('/register', function(req, res){
    var firstname = req.body.firstname,
        lastname  = req.body.lastname,
        email     = req.body.email,
        password  = req.body.password;


        console.log(email);
        console.log(firstname);
        console.log(lastname);
        console.log(password);

    if (email === null || password === null) {
        res.send(400);
    } else {
        Account.register(email, password, firstname, lastname);
        res.send(200);
    }
});

I can see that the listener in my app is being triggered when the form is submitted, but it is not getting the POST data i sent. In the browser console all i get for an error is "POST htp://localhost:3000/register 500 (Internal Server Error)"