c# - System.DirectoryServices.AccountManagement.dll issue with ASp.net mvc application -

relatively new deploying asp.net mvc application. have made change in project reading email using:

var user = system.directoryservices.accountmanagement.userprincipal.current.emailaddress; 

i referencing dll

c:\program files (x86)\reference assemblies\microsoft\framework.netframework\v4.5.1\system.directoryservices.accountmanagement.dll

i deploy application right click , publish. when run project on local machine current email in user variable works fine.

after deploy test server, user variable come null.

also observed bin folder not contain "system.directoryservices.accountmanagement.dll"

what doing wrong here? pointers? appreciate help.