Have you gone into your setting to ensure that you have that screen set as visible? Are you talking that the screen doesn't show or the map doesn't show on the screen? If it is the latter it could be in the card reader. Sometimes when I change cards it doesn't read it. Blowing into the slot will clear out dust and allow it to read for me
You probably weren't addressing me but, on mine, the chart is not even an option and it is not a setting. It automatically senses the GPS and will give you the chart (even if just the basic chart it comes with). It is like your unit does not think it has GPS.