How to change to new HTML page on Submit

I have a form with these properties:

<form action="php/registration.php" target="_blank" enctype="multipart/form-data" method="post" name="EventRegistration" id="EventRegistration" onsubmit="return Verify(this);">

<input type="submit" class="submit" value="Continue" onSubmit="location.href='thanks_event.html'" />

This opens a new window for the PHP backend page, and is supposed to change the form page to a “thank you” page, but it never happens. Something interferes with the onSubmit event for the submit button. I figured it was the form onsubmit event but removing that doesn’t make any difference. Syntax error? Does anyone know?