Grdredpol problem

hi everyone,

i’m testing the reduction to pole in gmt, with the grdredpol command. i saw that it optionally requires declination and inclination grid. i downloaded them for my area and tried to process like explain in the documentation examples:
grdredpol wdmam_italy.grd -Gred2pole_italy.grd -W5 -F45/45 -T2020 -Edeclin.grd/dip.grd -V

but the program give me the error:
grdredpol [ERROR]: Wrong method used to import grid

while it works when i use constant declination and dip, ex. with
grdredpol wdmam_italy.grd -Gred2pole_italy.grd -W5 -F45/45 -C4.88/56.87 -V

i also tried using only the inclination grid with the command:
grdredpol wdmam_italy.grd -Gred2pole_italy.grd -W5 -F45/45 -T2020 -Eidip.grd -V

and it works, even if it give me nan values in certain zone of the area.

someones tested same problems using declination and inclination grid files?

i attached input grid and declination/inclination grid test_red2pole.zip (697.0 KB)