Have you tried the codes for the TH-50PX50U? I have this Plasma and am using discrete codes for power on/off and a work around for the inputs. Here's the link to my file.

[Link: remotecentral.com]

Last time I checked the actual unzipped file says it's for a Pioneer but it is in fact for the Panasonic TH-50PX50U. I've asked Daniel to update the file so it reads "Panasonic" instead of "Pioneer". I don't know if he's done that yet or not but either way the file works great. Give it a shot and let me know how it works out for you.