My client had several MX900's that were the first gen that had to be programmed by the standalone editor. He upgraded his TV's to all Sony. I opened the standalone editor, updated it, popped the codes for the Sony (621) and downloaded to the remote. The TV would respond to the power on/of commands, but not the HDMI input commands. After burning through 2 hours trouble shooting, and updating the firmware, I still couldn't get it working. I have programmed up 1000's of remotes for Sony TV's, and I have never had an issue. Finally I grabbed a MX780, dumped code 621 in and it worked. I then proceeded to learn the commands into the old MX900's. This ended up working. I have no idea why code 621 would not work with the MX900, but it would not work with HDMI commands. Learning them form the 780 did work. I am still scratching my head.