I see the attachment now. I must have missed it.
I don't think you can use the "check new username" in the way you have tried. Instead just add a recordset to the page filtered by the emial address and then manually add an IF statement that redirects if the email isn't found.
You would filter where the email = the entered value and then use an IF statement like:
<?php
if ($CheckRS->TotalRows == 0) {
header("location: forgot-password.php?Alert=NoAccount");
die();
}
?>