After another 4 hours on the Logitech webpage, and after rearranging my system cables and renaming my inputs, I have given up trying to program the 550 to control my Mitsubishi LT-46231 television. The 550 is apparently incapable of doing the three-button sequence required to switch to the correct input devices. The Logitech webpage software doesn't even seem to have the correct names for the input buttons on the Mitsubishi remote --- it asks for "Menu" instead of the "List" button that I have to use to change inputs. I can make it work fine at the device level, but the Harmony software refuses (or is incapable) to send the signals for LIST ---> CYCLE ---> ENTER to correctly find my input names of SAT, VCR, or DVD for the TV activity or VCR activity or DVD activity. It cannot consistently find the correct input name. It will do it once in a while, then when I use a different activity, it loses its way again and I have to change inputs using the Mitsubishi remote. I have deleted the TV device and started from scratch many times. I have also used the "Troubleshooting" option on the Activity menu. The HELP button asks the appropriate questions, but cannot correct the problem. Nothing works and I am sending the confounded thing back!