captcha doesn't work on free web hosts

[Vladutu Teodor]

Hello,
I have a problem with recaptcha. I had installed it on my computer
xampp with apache and recaptcha works fine, but when I upload the .php
files on a free web host (like orgfree.com) and try to view the page,
captcha says: "Input error: Invalid referer". What does that mean? I
have already generated all possible keys (and test them) for my web
subdomain.

Thank you.