+ellps=airy +towgs84=446.448,-125.157,542.060,0.1502,0.2470,0.8421,-20.4894 +units=m +no_defs" To "+proj=longlat +a=6378137 +b=6378137 +datum=WGS84 +no_defs" But when I try to use a grid shift file for better accuracy I get a DLL Error 123. I'm using: