there seems to be something wrong. i set it up like you instructed, but it doesnt work. validation trigger is button submit press. i choose the validation type was like entry and choose the captcha variable then added it and the same as field i choose the captcha. and for the fail redirect to the form page.
then added a validation show if for the text "please try again" applied it to my form page and the fail i selected the like entry captcha and clicked ok.
i tested it locally with xxamp but wont work. i dont get an error msg on submit and it will submit successfully regardless if the entered captcha was incorrect.
then i uploaded it to http://webimpact.com.au/test/quote.php same thing happens.. but now the captcha image does not work?