HR24-500 not pulling in 1080p

I have a Sony Bravia KDL46HX800 which is hooked up to my HR24-500 through a 3D capable Denon AVR 1911 via HDMI cables.  When I run the Systems Setup/HDTV/TV Resolutions test for 1080p the receiver confirms that my equipment is capable of handling 1080p resoution.  However, I'm not ever seeing 1080p chosen when viewing live TV (like my local NBC, Comedy Central HD or Science Channel HD).  I've tried pressing the "Format" button on the remote, and physically pressing the receiver, but it will not choose (or let me choose) 1080p. 

I also ordered National Lampoon's Christmas Vacation in 1080p, and although I can't reconfirm it right now because it's already disappeared off of my recording list (very annoying) I recall that even then my receiver wouldn't get over to 1080p.  What's the deal with this?