HttpContext.Current.Request.ServerVariables["LOGON_USER"] return empty in remote server

I'm creating a WCF service for webapplication using jquery,javascript in a intranet set up so i need to send user information to the client which means who login to the website. Whenever i use HttpContext.Current.Request.ServerVariables["LOGON_USER"] in localhost it returns a username but not in remote server.
please somebody help me to get through this or atleast tell me is this possible or not
webConfig file
<?xml version="1.0"?> <configuration>   <system.web>         <customErrors mode="RemoteOnly" defaultRedirect="Default.aspx"/>   <compilation debug="true" targetFramework="4.0"/>         <authentication mode="None"></authentication>  </system.web>  <system.serviceModel>    &nbs ...