make sure that your access groups do not have any blank entries in them. They can be hard to spot, try to select the blank space below the last group entry, if you can select it, there is a blank entry you will need to delete.
when you make changes to the access groups , or access rules, you will need to re sync the WA_Security Assist folder on the server.
you say you are being denied access to the access denied page, have you applied an access rule to that page? How is the rule defined?
The access denied page should not have any access rules applied to it.