Please excuse me for I'm sure this has been asked but I can't find an answer to my question. I live in upstate NY in the middle of the finger lakes. I live on a lake so flying over water is part of my deal. I have finally grew a set and put my P4 over the water, heart pounding. I was flying approx. 120' altitude with VPS on the go app turned on. I looked at the bottom of my iPad and it said VPS N/A. I certain (somewhat) that it showed when I took off. Did this happen because I was over water?