Uncaught Type Error Problem

[pharma]

Hello, i can not figure out the simple problem here: 

Quiz.Game = function(game) {counter = 0;}Quiz.Game.prototype = {create: function() {button = this.add.sprite(100, 100, 'playbutton');button.inputEnabled = true;button.events.onInputDown.add(this.buttonDown, {num: 1});},buttonDown: function(num){counter++;console.log(counter);this.loadHighscores();},loadHighscores: function(){console.log('loadHighscores');}};

It throws the error: 

 

Uncaught TypeError: this.loadHighscores is not a function

 

What the **** is wrong with this.loadHighscores(); ?

 

Thanks!

 

 

[rich]

You've missed out the context parameter:

button.events.onInputDown.add(this.buttonDown, CONTEXT, {num: 1});