When you create a login page SA lets you define the page that is loaded when a login is successful. When you apply the SA Restrict Access behavior to that page you must have at minimum the "Logged into users" condition applied (set in the Rules Manager for setting up page access). Here you can apply other rules as well to restrict access.
Make sure that whatever rule you have applied to the login success page has the "Logged into users" condition applied. Double click on the SA Restrict Access to Page server behavior and then the Rules Manager to check. Also -- you can have only one "Allow" rule applied to a page. All others must be a "Restrict" rule.