Node.js update element in mongodb array

I have the following Mongoose schema and model:

//GameBoards
var gameBoardSchema = mongoose.Schema({
  mCurrentPlayer: Number,
  mCurrentPlayerName: String,
  mStarted: Boolean,
  mSwitching: Boolean,
  mFinished: Boolean,
  mPlayers: [{mPlayerId: String, mUsername: String, mHand: [{mValue: Number, mSuit:     String}], mFaceDown: [{mValue: Number, mSuit: String}], mFaceUp: [{mValue: Number, mSuit: String}], mPosition: Number, mSwitching: Boolean}],
  mDeck: [{mValue: Number, mSuit: String}],
  mPile: [{mValue: Number, mSuit: String}],
  mStartedAt: {type: Date},
  mLastUpdate: {type: Date},
  mChanceTaken: Boolean,
  mRoundLenght: Number,
  mNumberOfPlayers: Number,
  mLocked: Boolean
});
var GameBoard = mongoose.model('gameBoard', gameBoardSchema);

I already have a gameBoard in my database with four players. Now I'm trying to update a specific player in the database with the following command:

GameBoard.update({_id: game._id, "mPlayers.mUsername": updatedPlayer.mUsername}, {$set: {"mPlayers.$": updatedPlayer}}).exec();

But this does not seem to be working, but I get no error =/. I have tried to do a find with the same parameters and that works like a charm. Can someone pin point what I'm doing wrong?