如何在kohana中获得新的CAPTCHA图像

I'm using kohana 3.0 with kolanos-kohana-captcha-2ba7a6a module from earlier versions. Everything works fine, but I can't figure out one thing: how do I create new captcha image for current form? For example user can't read characters and clicks 'new image'. The ajax is sent, but the response is (almost always) the same image. In the controller, I tried the following:I'm using kohana 3.0 with kolanos-kohana-captch