CORS header not working in MEAN stack application

I am developing an application using the MEAN stack (Node.js, Express, AngularJS, and Mongoose). I have a basic understanding of the two. My API is running on a different port from my frontend, and because of this, I've included the CORS header in my API file. However, Chrome is still giving me this error:

XMLHttpRequest cannot load http://localhost:9000/#/.
No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'null' is therefore not allowed access. 

This is the header I've included in my API:

app.all('*', function(req, res, next) {
    res.header("Access-Control-Allow-Origin", "*");
    res.header("Access-Control-Allow-Headers", "X-Requested-With");
    next();
});

I have no idea where I'm going wrong. If it helps at all, I'm trying to load a user object in order to display information on a profile page. This is the code from my Profile Controller:

angular.module('angTestApp')
.controller('ProfileCtrl', function ($scope, $http) {
$http.get('http://localhost:8080/profile')
    .success(function (user) {
        $scope.user = user;
        console.log(user);
    });
});

EDIT Here's my server.js file if that helps: // server.js

// BASE SETUP
// =============================================================================

// call the packages we need
var express    = require('express');        // call express
var cors    = require('cors');
var app        = express();                 // define our app using express
var bodyParser = require('body-parser');
var mongoose = require('mongoose');
mongoose.connect('mongodb://test:test@novus.modulusmongo.net:27017/a3pemoGa')
var classroom = require('./app/models/classroom');
var article = require('./app/models/article');
var user = require('./app/models/user');


//From Tutorial
var passport = require('passport');
var flash    = require('connect-flash');

var morgan       = require('morgan');
var cookieParser = require('cookie-parser');
var session      = require('express-session');
// configure app to use bodyParser()
// this will let us get the data from a POST
app.use(bodyParser());
app.use(cors());
//app.use(express.static(__dirname + '/public'));

var port = process.env.PORT || 8080;        // set our port

// ROUTES FOR OUR API
// =============================================================================


// more routes for our API will happen here

// REGISTER OUR ROUTES -------------------------------

//From tutorial
// set up our express application
require('./app/config/passport')(passport); // pass passport for configuration
app.use(morgan('dev')); // log every request to the console
app.use(cookieParser()); // read cookies (needed for auth)
app.use(bodyParser.json()); // get information from html forms

app.set('view engine', 'ejs'); // set up ejs for templating

app.use(session({ secret: 'ilovescotchscotchyscotchscotch' })); // session secret
app.use(passport.initialize());
app.use(passport.session()); // persistent login sessions
app.use(flash()); // use connect-flash for flash messages stored in session


require('./app/API/routes')(app, passport);
//require('./app/API/general');
// START THE SERVER
// =============================================================================
app.listen(port);
console.log('Magic happens on port ' + port);
//exports = module.exports = app;