Captcha doesn't validate after upload to server
I have created the basic login/registration/forgot password pages. They are working. Captcha validation works when I run on my local machine using Apache and PHP 5.4.14. However, when I upload to my web server, which uses PHP 5.2.17, it fails with "Invalid information, please check your entries and try again."
Sticking with the "forgot password" page (looks like the same problem with registration): it turns out that the $_SESSION["captcha_Security_Code"] variable on the server is not set after the form is posted, which causes the validation to fail. I've attached my original forgotten password file, I made a few changes (removing the security answer) but they don't seem to matter. My question: have you seen this before? Do you know what the story is?