Because we don't want to give attackers an automated way to figure out
if they pressed the right button or not, we always redirect to the
"thank you" page - even if they click the wrong picture. So it is
working the way it was designed.
That said though, we are considering changing this to a redirect to
another set of pictures if the user makes a mistake although
supporting automated attacks is a big price to pay for that.
Best of luck.
-Anders