Problem with Page Sentry Function

Question

I am trying to implement a page sentry function for logging in to my application. In the authentication scheme for the application, I have created a scheme based on authentication scheme from gallery:No Authentication (using DAD) and made it current.
In the scheme, I have set the page sentry function to return lmf_siteminder_page_sentry; and the session not valid page to 104. I have made page 104 publicly accessible.
When I enter the application, APEX delivers me to page 104 as I would expect. The problem is that it does not seem to be executing my page sentry function. In that function the first thing that I do is log the application id and page number to a debug table. I never see an entry in the table for page 104. If I change the URL and go to page 103 (for example), I do see an entry for page 103 in the table.
What do I need to do to run my page sentry function on the default page?
Mike

Answer 1

Maybe I just don't understand APEX. I changed the call to my page sentry function in the authentication scheme. Basically, I put in a bad function name just to verify that APEX was using the value that put in there. What I found out is that if I am navigating to page 104 (my session not valid page), APEX never runs the page sentry function. If I navigate to any other page, APEX always runs the page sentry function.
So am I supposed to not set a session not valid page at all?
Mike