I hate to be redundant but what they both said is right. I did have to mess with your button to get it to post. I also had to edit the path for the captcha file in your index page. Other than that it works great. I got the "captcha is valid" message too. Here's my updated one.
EDIT: Haha, it seems that no matter what you put inside the box to match the captcha it will give out the same message. "The result code was valid!"