Does anybody know why I cannot get some HD channels on my HR21-200 in the living room but I CAN get them on my H23-600 in a different room? ESPNU is one and when I check signal strength it's always better on some sats on the H23. Does the DVR really need a stronger signal to receive??? I'm in a marginal area to receive a signal at all with a large hill to my south so I'm happy to get anything. thanks for any help.