arduino weather shield with gps
Until you have the correct baud rate and good satellite reception, many fields will be zero or empty.  I wrote a diagnostic program for NeoGPS that will try different baud rates and confirm that the GPS device is functioning.  The example program is in this directory:

examples/NMEAdiagnostic


Installation instructions are here.

If you're inside, you may not be able to receive anything.  Move next to a window or go outside.