Hi Fin - thanks for following up. The strangest thing indeed but it seems to have to do with defining the right sources for each of the overlay screen. For instance, I had depth on my gps and somehow the source changed to a copy of the sensor source that was not going anywhere. I wonder if I created this situation when I moved the transducer from Channel 2 to Channel 1. after I moved the overlay, the input on the chirp screen was not affcted until I change the data source as above. Does that make any sense?