Apparently, your direction buttons (up, down, left, right) are programmed for the cursor control of whatever device you are using for your channels (like a DVR, cable or sat box) with that activity you are on. When you go to Viera Link, you need to change to your Plasma through the Devices command of the remote. Make sure the direction buttons are programmed for the TV under Devices on MyHarmony.

OR, (As I've done) you can create an Activity that launches "Internet TV" and changes Direction control from my DVR to my TV.