Mongoose: Unable to populate self reference array, returns empty array

I'm trying to set a MongoDB database using Mongoose and I can't seem to make a self populate array work. Take a look at the code so you can get a better idea:

Here is the model code:

var Schema = _MONGOOSE.Schema;

var ModuleFields = Schema({

    name: {type : String, default : '', trim : true},

    label: {type : String, default : '', trim : true},

    required: {type : Boolean, default: false},

    type: {type : String, default: ''},

    multiple: {type : Boolean, default: true},

    predet: {type : Object, default: null},

    fields:[{type: Schema.Types.ObjectId, ref:'ModuleFields'}],

    createdAt  : {type : Date, default : Date.now},

    deletedAt : {type : Date}
});



ModuleFields.method({
    uploadAndSave: function (cb) {
        this.save(cb);
    }
});


ModuleFields.static({
    load: function (pName, cb) {
        this.findOne({name : pName})
          .populate('fields')
          .exec(cb)
    }
});

_MONGOOSE.model('ModuleFields', ModuleFields);

I added some data to the model, got no errors. Here is what I'm getting on the console:

> db.getCollectionNames()
[ "modulefields", "system.indexes" ]

> db.modulefields.findOne({name: 'video'})
{
    "__v" : 1,
    "_id" : ObjectId("52010bc4b2212caa01000001"),
    "createdAt" : ISODate("2013-08-06T14:44:20.149Z"),
    "deletedAt" : null,
    "fields" : [
        ObjectId("52010bd3b2212caa01000003")
    ],
    "label" : "videos",
    "multiple" : true,
    "name" : "video",
    "predet" : null,
    "required" : true,
    "type" : "custom"
}

So it seems to be ok, the reference is there in the array. When I look for the element it returns it, but the array is empty, here is a console.log of the data object that it finds:

    Object {id: "52010bc4b2212caa01000001", name: "video", label: "videos", multiple: true, type: "custom"…}
fields: Array[0]
id: "52010bc4b2212caa01000001"
label: "videos"
multiple: true
name: "video"
required: true
type: "custom"
__proto__: Object

There seems to be something wrong with the populate but I can't find it. If some can help me or point me in the right direction to read about this I would really appreciate it.