first of all: Hello

And next: I've got a problem. I enabled captcha on my site. It's cool, image is loading but there is no characters on it. However I can find it in database. I was searching this forum for an answer but I did not find anything about my problem (maybe I was not looking good

Would you help me?
captcha.php looks ok.
EDIT:
libraries like truefonts and gd are installed on my server.
Link to my site: CLICK