Remote not turning the Zenith Plasma Display Panel TV on/off.

the remotes are usually multi function .. that is, they can control more than just the TV .. make sure TV mode is selected ... if its in VCR mode or Cable or whatever then it wont control the TV .. if its a programmable remote then it may have lost its program and would have to be set up again ... if its the original that came with the tv then that shouldnt happen . once in a while but not often i see a bad LED (at the tip of the remote) ... those are infra red so you cant see the light beam but a digital camera can .. point the remote at the digital camera and you should see the LED flashing in the cameras viewer when a button on the remote is pushed ...