错误400 jQuery + Yii

I have an AJAX call in my view to an action in my controller. However, I always get an Error 400. Below is the code for my AJAX call:

    $.ajax({
        cache: false,
        url: '/dummy/index.php/module/controller/checkCross',
        dataType: 'json',
        type: 'POST',
        data : {"male":parents[0],"female":parents[1]},
        success: function(result){
            alert(result);
        }
    });

Below is the code in the controller:

 public function actionCheckCross(){

     if(Yii::app()->request->isPostRequest) { // check if POST
        $flag = CrossingMatrix::model()->checkParentsIfCrossed($_POST['male'],$_POST['female']);

        if($flag){
            return true;
        }

        else{
            return false;
        }

    } else { // direct URL request will be GET, so show error
        throw new CHttpException(400, Yii::t('app', 'Direct access is not allowed.'));
    }

}

Any ideas?

You are expecting json data, but you send empty page to browser. You should encode result like that:

echo CJavascript::jsonEncode((bool)$flag);
Yii::app()->end();

In your code you returned value. Notice that your yii exception message is Direct access is not allowed but your error is Your request is invalid.