How to Pass Username in Header from F5 Login Page

I have configured a Web Application Access Management for Local Traffic Virtual Servers using the wizards in APM wherein i am redirecting a user to a portal upon authentication using F5 Login page integrated with AD in backend. The access policy of the above mentioned VS is

I am successfully able to login and redirect the user to the home page of the portal.

But i also need to pass the username entered in the username filed in login page in header so that the portal at the backend may identify the user and display its name.

for this i have created a iRule :

when ACCESS_ACL_ALLOWED { set myusername [HTTP::header username] } when HTTP_REQUEST_RELEASE { if { [info exists myusername] } { HTTP::header replace username $myusername } }

    But i am still unable to do so. Kinldy help.