Issues with forgotten password page.

Using security assist, I have created the appropriate pages, but am having a small issue with the password reminder page, which I cannot work out.
If the user enters the wrong login details, they are redirected to the forgotten password page, where they are given the option of trying to login again or have the password reset and emailed.
If the user enters an email address which is in the visitors table, the password is updated, the email is sent, and the user is redirected to a suitable page - this works fine.

If the user enters an email address which is NOT in the visitors table, nothing happens, the form doesn’t post.
In this instance, I would like to either…
Redirect to a different page with a suitable message, or preferably, check for a form post, and display a suitable message on the same page.
I have tried adding code to display a message on the form being posted, but nothing ever appears