Did you remove the original access restriction rule that was in place on the PowerCMS pages? If the old rule is still there you will not be able to access the pages by just being logged in. One way you can test your rule is to create a new blank page and apply the rule to it, then login and visit your new page. If you pass the rule you will have access to the page. If so this indicates that your login page and logged in rule is working ok and that there is another restriction on the pages that is preventing you from accessing them.
For reference the access restriction rule that is on the PowerCMS pages by default looks like this:
php:
if (!WA_Auth_RulePasses("Administrator")){
WA_Auth_RestrictAccess("users_login.php");
}
