asp.net - The remote name could not be resolved: 'graph.facebook.com' on ASP .NET Application -


i'm having trouble when using facebook login button. i'm using oauthwebsecurity.registerfacebookclient() authentication process stopped working properly.

when click on login button can go facebook enter account (if needed) , fails on callback , then error pops up.

my externallogincallback code this

authenticationresult result = oauthwebsecurity.verifyauthentication(url.action("externallogincallback", new { returnurl = returnurl }));         if (!result.issuccessful)         {             return redirecttoaction("externalloginfailure");         }          string fbid = "";         string first_name = "";         string last_name = "";         string email = "";          if (result.extradata.keys.contains("accesstoken"))         {             var client = new facebookclient(result.extradata["accesstoken"]);              dynamic me = client.get("me", new { fields = "email" });              session["facebooktoken"] = result.extradata["accesstoken"];              fbid = result.extradata["id"];              email = me.email;         }         else         {             string[] full_name = result.extradata["name"].tostring().split(' ');              if (full_name[0] != null)                 first_name = full_name[0];              if (full_name[1] != null)                 last_name = full_name[1];         }          if (oauthwebsecurity.login(result.provider, result.provideruserid, createpersistentcookie: false))         {             setauthcookie(email);             setencryptedcookie(configuration.usercookie, email, configuration.cookielifetime);              if (request.cookies["isfromcheckout"] != null)             {                 setcookie("isfromcheckout", false, false);                 removecookie("isfromcheckout");                 return redirecttoaction("cart", "store");             }             if (returnurl != null)             {                 return redirect(returnurl);             }             return redirecttoaction("index", "store");         }           if (user.identity.isauthenticated)         {             // if current user logged in add new account             oauthwebsecurity.createorupdateaccount(result.provider, result.provideruserid, email);             setauthcookie(email);             setencryptedcookie(configuration.usercookie, email, configuration.cookielifetime);             userservice.lastseenupdate(email);             if (request.cookies["isfromcheckout"] != null)             {                 setcookie("isfromcheckout", false, false);                 removecookie("isfromcheckout");                 return redirecttoaction("cart", "store");             }             return redirecttoaction("index", "store");         }         else         {             // user new, ask desired membership name             string logindata = oauthwebsecurity.serializeprovideruserid(result.provider, result.provideruserid);             viewbag.providerdisplayname = oauthwebsecurity.getoauthclientdata(result.provider).displayname;             viewbag.returnurl = returnurl;              return view("externalloginconfirmation", new registerexternalloginmodel             {                 id = fbid,                 username = email,                 externallogindata = logindata,             });         } 

this error shows when test on production , not while debugging.