Here's a real mystery - Installed a new HR34 (F/W 4C9; SD GUI) along with a AM21N OTA adapter. Selected St. Louis, MO/E. St. Louis, IL "market" and HR34 IDed most (but not all) OTA channels. Next, installed a AM21N on a previously activated HR24 (F/W 57B; HD GUI) and selected the same "market". HOWEVER, the HR24 IDed a completely DIFFERENT list of OTA channels. The HR24 list is valid for this "market" but it omits a couple of the low-power channels listed in the HR34 list and includes a valid sub-channel not contained in the HR34 list. Can anyone explain why two receivers would ID a completely different list of available OTA channels for a given market? Thanks!