LB::status not returning session_disabled status

Hello,

I have the following irule:

when LB_FAILED {
   switch -glob [LB::status] {
      "session_disabled" {
         switch -glob [HTTP::uri] {
            "/maintenance_img.png" {
               HTTP::respond 503 content [ifile get "maintenance_img"]
            }
            default {
               HTTP::respond 503 content [ifile get "maintenance_page"]
            }
         }
      }
      "down" {
         set response "Loading"
      }
   }
}

But it appears to never return a "session_disabled" state.

The pool has 2 members with one member "forced offline". When i disable the active member in the pool,

HTTP::respond 200 content [LB::status]

always returns "down".

Is this because of the way the LB selection process works? How might I test for session_disabled properly.

As you may deduce i am attempting to display a maintenance page when the nodes are "session_disabled" and a "loading" type page when the nodes are down inexplicabbly (which usually lasts <30 secs).

thank you!

-van