You have bench mark locations but they are not in Latitude and Longitude.

Symptoms:

If you are attempting to calibrate your GPS against a design and you have known bench mark locations you can use the “Enter a known location” option to achieve this. However you may find that your bench mark values do not match any of the formats requested.

Cause:

Your bench mark locations are in an incompatible projection or coordinate system. Commonly they are in UTM easting or northings or similar.

Solutions:

Contact your provider and request the bench mark locations in WGS84 Latitude and Longitude format. If possible, request that they use ‘decimal degrees’.