This app doesnt seem to work properly

Yesterday I added a new record (the only record, just after install) and entered the Miles as 123000 because the car has done 123000 miles
Today I added a new record with 123500 miles and fuelpad calculated the trip to be -123000
I added another record for 123800 and again the trip was -123000
I added another record for 123900 and again the trip was -123000

I gave up