socket.io.js not found

For some reason my node server cannot serve the route /socket.io/socket.io.js, I always get a 404 error.
I tried compiling different node versions (current is 0.6.13 which also runs on server, where it actually works).
From the app.js I get info: socket.io started and no error when trying to call the socket.io.js.

I try it from localhost and port 8000 and I use the express framework

This is the code from app.js:

var express = require('express')
  , app = require('express').createServer()
  , io = require('socket.io').listen(app, { log: true });

app.listen(8000);

app.configure(function() {
    app.use(express.static(__dirname + '/public'));
    app.use(express.errorHandler({ dumpExceptions: true, showStack: true }));
});

io.sockets.on('connection', function (socket) {
   // all other stuff here