Why does no-frost freezer has ice forming on inside?

I agree with Bruce and would add that if the drain tube to the evaporation pan is plugged or covered with something , the water would have a tendency to run out the door. That is until the darn thing makes ice out of the water again when the defrost cycle is over. Then you would have ice on the back before the next defrost and ice on the bottom and ice at the door. Make sure there is nothing plugging the line out the bottom of the freezer to the evaporation pan.