redirect problem

hello,
i’ve encountered a small, but annoying problem.
everytime i hit “submit post” i get to the redirected page, even
if it is an invalid post (wrong answer at anti-spam question, blank fields etc.).
the post is not made, which is good, but i still get redirected.
the error-flag is in the url, but no message in the site.
(only get the error message, if i put the shortcode on the target-page too)

is there a posibility to check the form first and then get the error-message or the redirect?

thx

http://wordpress.org/extend/plugins/user-submitted-posts/