irule apology page logo/image not working

The first thing I'd do is log the traffic and see if the logic is correct:

if { [HTTP::header referer] eq "" } {
    log local0. "uri = [HTTP::uri]"
    switch [HTTP::uri] {
        "/apology.jpg" { 
            log local0. "apology"
            HTTP::respond 200 content [ifile get "apology.jpg"] 
        }
        default { 
            log local0. "default"
            HTTP::respond 200 content [ifile get "access_denied.htm"] 
        }
    }
}

If you see "uri = /apology.jpg" and then "apology" in the LTM log, then you know the iRule logic is good and there's something else going on.