I enter the correct verification number, but the form does not accept it. Why?
If cookies were already enabled in your browser, delete them (Delete cookies), type in the verification number and submit the form.
To avoid using cookies, set the CAPTCHA protection to Daily Changed CAPTCHA.
To avoid cookies completely, set the CAPTCHA protection to None and protect the form by limiting the number of submissions received from an IP address to 1 or 2 per day. This way, you’re form will not be spammed and the verification image will not be required anymore.