Trying to read post in node.js

lookup.js

var app = express.createServer(express.logger(), express.bodyParser(), function(req, res){
  switch (req.url) {
    case '/':
      res.write(
        '<h1>ZIP Lookup</h1>'+
        '<form method="post" action="/lookup" enctype="multipart/form-data">'+
          '<fieldset>'+
            '<label for="zip">Zip: </label>'+
            '<input type="text" name="zip" id="zip"></input>'+
            '<input type="submit" value="Submit" />'+
          '</fieldset>'+
        '</form>'
      );
      res.end();
      break;
    case '/lookup':
      if (req.method == 'POST') {
        res.write('Zip: ' + req.body.zip);
      }
      res.end();
      break;
  }
}).listen(3000,"127.0.0.1");
sys.puts("Server running on port 3000");