With hr24 being a second receiver, are you attempting to program the av1 or av2 device? Those devices won't take the RF remote programming unless it first has an IR code from 00001-00008 programmed to it.
Well I made another RF remote gain this afternoon. I have a Sharp Aquos 32" TV a friend gave me for my office. He took it out of his motorhome, and it was a great display. It has this large external multi-media box that is remote to the TV. So I took an old RC64R and programmed it for RF on the H20-100 was was able to move the DTV receiver off to the side on a desk/book case. TV IR sensor is on the display, so I can now run this setup without worrying about the separation of the devices. The multi-media box has a TV input, so I have my display on DVI and can use the TV as a second display on a VGA cable.
Now if I can get the HR24-100 working on RF I can install a nice smoked doors to hide it, the router and I bunch of other components in two levels of that entertainment center. I have a couple new RC66RX's coming to start fresh with that challenge.