grunt not launching my nodejs server

I'm trying nodejs to build a webapp and I'm trying to work with grunt

this is the content of my current directory

C:\data\nodeprojects>dir

 Répertoire de C:\data\nodeprojects
08/15/2014  01:48 PM    <DIR>          .
08/15/2014  01:48 PM    <DIR>          ..
08/15/2014  05:24 PM               238 gruntfile.js
08/15/2014  01:44 PM    <DIR>          node_modules
08/15/2014  01:45 PM               316 package.json
08/15/2014  01:08 PM                54 readme
08/15/2014  02:34 PM               526 server.js
               4 fichier(s)            1,134 octets
               3 Rép(s)  118,564,114,432 octets libres

and when I launch my nodejs server I get the following :

C:\data\nodeprojects>node server.js
Server is listening
_

after that I can go to my web browser, access to my localhost, and see a pretty nice hello world page.

But my problem is the following :

This is the content of my gruntfile.js :

module.exports = function(grunt) {

  grunt.initConfig({

    pkg: grunt.file.readJSON('package.json'),

    nodemon : {

        dev : {
            sript: 'server.js'
        }
    }
  });

  grunt.loadNpmTasks('grunt-nodemon');

}

when I launch grunt nodemon ths is what I see :

C:\data\nodeprojects\bubblepeople>grunt nodemon
Running "nodemon:dev" (nodemon) task
_

I guess grunt is actually running, but I think it didn't launch my server.js script, I should see my server.js output (Server is listening). And, of course when I go to my browser, I can't access to my local website anymore.

I know my grunfile seems a bit short, but I thougth this was enought to run my script with nodemon using grunt.

Do someone know what I am doing wrong here ?

thx