I had similar problem operating my Panasonic TV using Roku remote to turn off power or control volume. After a google search i followed the steps listed below and my Roku remote now is able to turn off power and control volume.
Press the Home button. on yourRokuenhancedremote.
Scroll up or down and select Settings.
Select Remotes & devices and then selectRemote.
Select Set upremoteforTVcontrol.
Follow the on-screen prompts to complete the process.
In case anyone else runs across this... I also have a Panasonic plasma TV. Mine is connected to the Roku through a receiver. To finally get my remote to detect the TV and then find the correct code to operate the volume and power I had to do the following:
- Connect the Roku directly to the TV.
- Use a newer high quality HDMI cable.
- Once the Roku was connected directly via a decent HDMI cable, then reboot the Roku.
After this the normal setup process where it plays music and tries to mute the TV worked. Once the remote was programmed for the TV, I was able to reconnect through my receiver. Now through DLNA between the TV and receiver, and the Roku remote IR, I can turn everything on/off and adjust the volume of both through the Roku remote.