I just setup a new HR24 and am getting error 721 channel not purchased for all Showtime channels and some HBO channels. Everything else works fine. My other HR24 in an adjacent room gets reception on these channels. I've reset the new receiver several times and triple checked the settings. Setting it up in another room that works didn't help. I've also gone through troubleshooting with DTV over the phone several times and nothing has fixed the issue. According to DTV, its a problem with the box, which I bought from 6th ave. I'm a bit skeptical that this is the case. Any thoughts?