find country name from ip address using c#

Question

 

i want to getiing country name from ip address :

my code is :

 

string ip = Request.UserHostAddress;

GeoService.GeoIPService service = new GeoService.GeoIPService();

GeoService.GeoIP output = service.GetGeoIP(ip);

string country = output.CountryName;

 

but getting error