knockoutjs “Impossible d'analyser les liaisons” erreur, mais le code fonctionne

J'ai été en utilisant knock-out pour un moment, mais en écrivant quelques exemples de code, cela m'a déconcerté. Le code fonctionne exactement comme je l'attends, où la cliquez sur ce bouton active le visible, mais je suis toujours une erreur:

JsFiddle: http://jsfiddle.net/JasonMore/hCdF8/1/

Uncaught Error: Unable to parse bindings.
Message: ReferenceError: answerClick is not defined;
Bindings value: click: answerClick

de

<ul data-bind="foreach: answers">
<li>
<a class="hiddenButton" href="#" data-bind="click: answerClick" />
<div class="answerNumber" data-bind="visible: showAnswerNumber">
<h2 data-bind="text: answerNumber" />
</div>
<div class="answer" data-bind="visible: showAnswerText">
<p data-bind="text:text" />
<p data-bind="text: points" />
</div>
</li>
</ul>
<script type="text/javascript">
var answerViewModel = function () {
var self = this;
//clicks
self.answerClick = function () {
self.showAnswerNumber(!self.showAnswerNumber());
};
//observables
self.answerNumber = ko.observable();
self.text = ko.observable();
self.points = ko.observable();
self.showAnswerNumber = ko.observable(true);
//computed
self.showAnswerText = ko.computed(function () {
return !self.showAnswerNumber();
});
};
var roundViewModel = function () {
var self = this;
self.answers = ko.observableArray();
};
var answer1 = new answerViewModel();
answer1.text = "foo answer";
answer1.answerNumber = 1;
answer1.points = 50;
var vm = new roundViewModel();
vm.answers.push(answer1);
ko.applyBindings(vm);
</script>