You are using the Dreamweaver Page access restriction behavior.
you will need to use the security access restriction behavior instead since you are using the security assist login.
Go to WebAssist -> Security Assist -> Manage Site Access -> Access Pages Manager.
select the pages that should be restricted, and select the access rule to apply.
if no rules are defined, click the Access Rules button to open the Access Rules Manager panel and define a rule.
For basic access rule, use the memID session that is created by the login page, set the rule to:
Value: Click the lightning bolt and select the memID session variable
Compare to: leave this blank
In other words:
Allow IF the memID session variable is not empty