When you use security assist to generate the pages, there is an option in the wizard top allow auto login.
When you select this option, it will add 2 instances of the Security Assist Authenticate user server behavior on the login page.
You have a problem on your current login page. You removed the instance of the login that would be run if the form where submitted and left behind only the auto login instance. There is no way that your current login form will ever allow another user to login.
recreate the security assist pages, this time, do not include the auto login or remember me options.
when you add the insert record behavior, set the Redirect after inserting to go to the logout page.