MyBB Community Forums

Well, i have a mybb board (http://animania.manganime.biz/bakacafe/index.php), but im facing some problems.

If i don't have the captcha option turned on, many bots register in my forum. If i have the captcha turned on, the captcha imagem doesn't show.
I've searched, but i didn't find any tips how to solve this problem.
Cumps.

Reupload a new copy of ./captcha.php from a fresh download. Have you edited any other files??

I've reuploaded, but it didn't solved the problem. No, i haven't edited any files.