Thanks for your help RV8JD,must watch my updates.A good lesson!You may have an older version of the software. It looks like that error was introduced in v16.2.4. It was fixed in v16.3.0. Updating to the latest SW version (v16.4.4) should fix it. Others saw the same thing as you, see this thread for details:
Add Fuel menu
Since the last version update, (it was 16.2.4), When I go to the add fuel menu, the current quantity always reads as 0.0, no matter how much fuel is indicated on the fuel remaining widget.forum.flydynon.com