Cgi.remote_user

Hi
Im having a problem trying to display the Remote_User on a form using coldfusion, It keeps showing blank

When I dump out the values using the below code its showing an empty string for Remote User but all other details are been displayed, IP address etc
<cfdump var=“#CGI#”>

It works on other servers but not the one im currently using, is there any settings I need to configure on the server? if so can you advise

Thanks
Damien