Yes, I think Kev re-iterated my thoughts. The one other thing I found with a brief scan through is that you also need to make real sure the date and year and time are set correctly.
I don't mean to badger about this, but I'm hopeful (sure?) you're already doing this. And I did find it necessary, sometimes, when I was fiddling around with mine, to have to unplug and replug the wall wart to get a reset. The WxPic doesn't automatically reset all the time.
some of the plug in readouts seem to be a bit more sensitive, depending upon the function you've set them to, especially historical highs. lows, etc.
Keep trying, it will come along. Peet stuff is pretty darn good.
Dale