Understanding difficulty when using expressJS and spookyJS

I'm currently using expressJS to make a navigation for a nodeJS server and spookyJS for testing and I'd like to know if following code could work.

When a user visits http://localhost:3131/tests he sees a html site. This is working perfectly.

Example Code:

app.get('/tests', function (req, res)
{
    res.render('tests.html');
});

When a user visits http://localhost:1337/tests/start the spookyJS tests should start but this isn't the case.

Example Code:

app.get('/tests/start', function (req, res)
{
   try {
    var Spooky = require('spooky');
} catch (e) {
    var Spooky = require('../../lib/spooky');
}

var spooky = new Spooky({
        casper: {
            logLevel: 'debug',
            verbose: true
        }
    }, function (err) {
        if (err) {
            e = new Error('Failed to initialize SpookyJS');
            e.details = err;
            throw e;
        }

        spooky.on('error', function (e) {
            console.error(e);
        }); ......

The code above isn't the full code it's just to give you an insight how I'd like to do it. Is it possible to do it this way with expressJS?

I have made another little example which works. The tests are starting when I navigate to an nodeJS server in my browser like in following example http://localhost:4141

var httpServer = require('http').createServer(function(req, response){
try {
        var Spooky = require('spooky');
    } catch (e) {
        var Spooky = require('../../lib/spooky');
    }

    var spooky = new Spooky({
            casper: {
                logLevel: 'debug',
                verbose: true
            }
.
.
.
.
});
httpServer.listen(1337);

Why is it working when I use a normal nodeJS Server without navigation but with the expressJS navigation it isn't working? Thank you for your help, Alex